let's step back and think about the natural world let's step back and think about biology step back and think about the diversity of life life is amazing and complex this is reflected in the different animals and plants and various things that we can measure in biology but what I would like to argue today is that despite this diversity despite these differences between organisms despite the differences in how they interact with each other that there are underlying unities of life these unities of life have actually been known more or less for a quite long time to essentially since the beginnings of biology okay and this unity of life is actually reflected and what I'm going to call biological time so the diversity of life and let's think about time in particular how long things live right so we can think about microbes lifespans minutes two hours as a mayfly was about 24 hours nice drone ant lives in the

order about three weeks house mice about a year they're lucky

domestic rabbit 8 to 12 years putting activity maybe a little bit more but the world record of animals in terms of living is this creature right here this

is the bowhead whale lives approximately two hundred and eleven years old but in terms of living things there's things that actually live longer than this so this is the General Sherman tree in California this is the giant sequoia estimated to be approximately 2500 years old this one individual organisms can actually live longer than this in fact the for a single single individual in terms of maximum lifespan unfortunately it's not living today because unfortunately it was cut down and in the process of cutting it down and Counting the tree rings they discovered that it was the oldest tree ever recorded Methuselah 5000 65 years old oldest known living non clonal organism okay but what about us this is Jean Louise Clement good oldest living human ever recorded she was a hundred and twenty-two years old and one hundred sixty-four days we get that old these days are important right she was born in 1875 14 years before the Eiffel Tower was constructed she used to sell painting canvases to Van Gogh she died in 1997 she started smoking at the age of 16 and she quit when she was 117 she smoked not only one or two cigarettes a day but no more than that and she also had a glass support everyday the secret of her longevity she says was eating chocolate breaking ports and rubbing olive oil over her skin 122 years so time I whole time is what a clock reads right to know the time to go to the clock to watch the passage of time you watch the clock time passes at a constant rate in terms of the history of science we can really go back and characterize the history of science in terms of our abilities to characterize and measure time scientific progress is really reflected by this in continuous improvement of measuring time from things like Stonehenge to this early mechanical clocks such as the one in Prague in the Czech Republic the uncertainty of these early clocks spanned on this no time order of noun may be days or hours up until modern day with her modern atomic clocks our uncertainty in measuring time now is one second in one I'm sorry in 30 million years that's how accurate our timekeeping is now so these clicks these clocks all

tick along at the same time scale but this ticking of the clock like to

emphasize is on a time scale relative to how we perceive the passage of time right so good is our ability to characterize time we can go back in time and characterize very accurately with

many different methods the geological time scale and we can place this geological time scale in the context of

biology so we know approximately the earth is 4.8 billion years old we know

that life arose approximately 3.5 billion years ago but life really didn't

take off that is the diversity of forms that we see all around us until the Precambrian approximately 541 million

years ago and during this time this is where the major clades arose in terms of

what we see today in terms of the diversity of life

so unlike our timekeeping with clocks what I would like to emphasize today is

that biological time is different biological time is relative so let's

think about taking a walk in a forest right pleasant day you go through you see the breeze well you hear the breeze

you feel the breeze on your neck you see the leaves moving in the winds but if

you watch the trees besides bending in the wind they don't seem to do much so

what if we had the ability to take something like a forest and speed up human time basically compress human time

of one year compress it down to 30 seconds and take that same forest and

scale the time scale of a forest so that human time and forest time merges so

let's alter the temporal scale of a forest and this slow biology that we see

in the forest appears to come alive so I screenshots stole a very cool PBS

special that I saw about a year ago this is the life of plants and so what I'm

going to show you is a time-lapse recording where they move then a camera then through a forest on the time scale

of about a growing season about a year and you're gonna see plants come alive growing at the speed at which we would

perceive them if they lived and operated on human time flowers grow and most

instantaneously Moss shimmers in the light we see branches slowly start

extending flowers are born then they die seeds come to life relatively quickly

plants begin to explore the light environment moving the branches up and down vines seem to spin in the air as

they search for various places to go and fungi seem to grow quite rapidly so

increasingly we're able to view biology on the timescales that we perceive time so does biological time

tick or pass at a constant rate so i'mma

argue is that no it doesn't life's perception of time is different than geological time but biological time does

have constants and it's these constants that we're just starting to understand but they also have a long history in

biology and to boil down these biological constants we don't understand

where they come from to make sense a biological time we need to understand

something about scaling so to understand

the dimensions of biological time actually requires five different insights okay so let's move through

these five different insights okay first let me give you a quick scaling primer

in one slide so understanding of scaling actually goes back to Galileo in 1638

and so many of you already know basics of scaling basic math you take in

primary school so if we want to take a simple Euclidean object such as a cube

and blow it up in size we actually know how the volume and how the areas and the

surface areas then will then change as we go from small then to large we know that the area then of a cube is going to

be its length squared and its volume is going to be its length cubed and so

Galileo actually effectively not only went back to these principles of signal tune but he realized that within biology

if you take the bone of a small Mouse and a bone of an elephant and you scale

them appropriately so that they're on plotted on the same size scale what you can tell is that

gravity is more important for the elephant that it is for the mouse

because of the because of gravity bones have to scale differently than what you

would expect from the simple scaling of a cube or fear or so on and so Galileo used this

principle of scaling to infer deeper insights into biology okay so the second

insight I would like to pass along is that biological rates scale biological

time scale so this is the animal physiologist max Cliver

1938 and one of Max's claims of fame in terms of one of the most important

things that he discovered was how the metabolic rate of an animal changes as

it changes in size and actually this is one of my favorite biological graphs they like to teach to my undergraduates

because this is one of the only graphs that I know of where you actually have a man and a woman plotted on the same plot

together now we've come a long ways phylogenetically in terms of how we understand these relationships but here

we have things like my small Birds elephants horses man and women all

together on the same plot together this is called a mouse - elephant curve okay so early on what Max Kleiber noted is

that as you go from small sizes to large sizes the metabolic rate that is how

much energy and animal needs to live increases with its sides but the other

thing that he noticed was that it wasn't just a simple straight line what he noted was that the slope of that line is

actually 3 over 4 or 0.75 and at the

time that was very interesting because it went totally against what most people in biology thought that this

relationship should look like if you double the size of the animal do you double the amount of food that you get

it rhetorical question the answer is no because this dotted line is a one-to-one

line that's the doubling line this other dotted line is blue dotted line here is

the 2/3 line that is if the amount of energy and animal needs is proportioned

to its surface area remember the example of a cube going from small cubes to large cubes

if your metabolism is proportional to your surface area of your body we would

expect the surface rule to have a different slope of 2/3 and over and over

again this launched a huge debate in biology why does biological rates and times

scale with a slope or an exponent that's differ from the 2/3 or that simul to

drool from Galileo so biology isn't

simple Euclidean geometry now we can

fast forward many decades many years and what we begin to identify is that there

appears to be more Universal biological scaling functions so can we take the

diversity of life and make sense in terms of how life works in the scaling

framework so let's look at this same graph again this is body mass small size large size and Hritik plot a measure of

growth rate how fast an organism grows so let's put some insects on the graph

let's put some birds also on the graph let's put some fish some plants some

mammals some protists some zooplankton

would it be great if you could put some dinosaurs on there - well actually turns out if you cut open the dinosaur bone

you actually see rings like a tree ring in a dinosaur bone all right actually in

a lot of reptiles today you can count how old they are based on the rings then within their bones and it turns out when

you do that based on some other biological knowledge we can get an estimate of the growth rate of dinosaurs

and there they are so all organisms appear to be described

by an approximate scaling function and the slope is approximately 3 over 4 and

not 2 over 3 so what is the 3 over 4 or

the 7 5 scaling relation it mean well if we do some quick math so

this is metabolism mass to the 3/4 if I look at the metabolism per unit mass how

much energy it takes to support a given mass of animal what you actually find is

that as you go from small things to large things and metabolic rate per cell

decreases a small organism has an incredible metabolic rate in that cell

whereas a large animal such as an elephant has a much lower metabolic rate

we see these relationships almost everywhere we look this is heart rate going from small mammals to big ones

number of beats per minute how fast your heart is beating look at a whale 20

beats per minute we can go up to a human bump 70 beats per minute look at a shrew

smallest mammal 600 beats per minute if you've ever held a shrew it's like

they're vibrating mutation rate how fast

new bits of information are entered into the genomes we look at small organisms - large small organisms have a higher

mutation rate larger organisms have a lower mutation rate okay so the third

bit of insight biological times scale so

across biology biological times scale as approximately their size to the

one-fourth power any timing critical life timing that you can measure ranging

from body cycles such as respiratory cycle how fast your muscles contract your cardiac cycle physiological times

your circulation of blood how fast it takes you to clear insulin the plasma

high flyff of given different metabolites your metabolism of fat

growth and reproductive times how long it takes then for an organism of given

size to reach reproductive age but also ultimately your lifespan in ecology so

this is a summary of many different birds the slopes of these different relationships are all clustering around

1/4 so biological times warp the bigger you are the longer it takes to do things

so this is a fun little bit of biology so let's think about pregnancy in terms

of how long different animals it takes for them to give birth ok so I'm showing you how long it some great pictures of

developing zygote here of an elephant ok small mouse if we plot then differences

in body size in these different organisms versus gestation period how long then mom is pregnant right it

scales as mass of a 1/4 and larger organisms take longer to give birth but

what's interesting is that as then the developing fetus is growing within mom

the metabolic rate of the youngster while it's inside mom its metabolic rate

goes as the metabolic rate of mom but as soon as you're born your metabolic rate

increases appropriate to the size at which you are born so at birth metabolic

rate then scales like any other mammal of a given size so biological rates and

times scale biological time changes it's

as if biological times warped ok salvadore looks on so why is this why do

larger organisms live longer why do small ones live such a short time so is this just numerology this three

over four this one fourth and so on well it actually turns out that there are a lot of different quarter powers in

biology 1/12 3/8 3/4 and 1/4 we seem to

see these in many different organisms and so this suggests that there may be

something deeper there may be some deeper biological truths in particular it suggests that deep down biological

time is regulated or controlled in some sort of way

okay so number five bits of insight that I would like to pass along what's the fourth one the fourth one actually comes

from trying to understand why we see such variation in biological time and

that is having to do with networks so

earlier with work from Geoffrey West who's actually a trained physicist at

Los Alamos National Labs and at the time my adviser Jim Brown at the University of New Mexico we started not only

pondering these different patterns in biology but we wanted to know whether or not we could construct an argument for

why we see these prominent patterns in biology and here's the assumption is that even

you as you're sitting there if we dissolved away your skin you are a sitting Network fact most of biology is

a network a vascular Network a network of pipes and plumbing of that nellie

disperses resources through the body but also transfers information and the assumption of this work is that these

biological scaling laws originate in the size and the geometry of these hierarchical tree like networks so if

you strip away your skin and you compare your vascular network to a tree

mathematically networks the plants and animals are remarkably similar to each other but we've actually known this for

a while in fact it was Leonardo da Vinci who after a series of different

paintings of landscapes realize that it was an easy way to paint a tree he

called it the area preservation room and so from Leonardo's notebooks we can work out how he actually worked it out but

what he discovered was that as you follow a tree from the base of a tree all the way to the tips then of the tree

this network is area preserving that is if we calculate the cross-sectional area

that mother branch here at the base and we calculate the cross-sectional area of all the twigs at the tip the area is

it's the same cross-sectional area so if you want to know the cross sectional area of a trunk of a tree count up the

cross sectional area of all the tips of the terminal branches we've done that I

wouldn't pass along that fate to anyone it's a hard work but in general area preservation seems to be the rule so

networks quarter power scaling the first hypothesis is that cellular metabolism

is a unifying measure of life we can measure metabolism now I the individual

scales but also its scales of the ecosystem metabolism controls the pace

form and diversity of life but what controls the pace of cellular metabolism

ultimately you can drill down to your cells remember your basic biology well the mitochondria here is ultimately

responsible and for the flux of energy than through the cell in particular we can drill down even further to sign a

chrome oxidase which is remarkably similar across life but there's a bigger

an important problem here if ultimately metabolism that is being done within

mitochondria and thanks to the cytochrome oxidase molecule a problem

that is how do we get resources to fuel your sounds how do we supply all of your

cells within your body so let's use an analogy right how do we design an

optimal Network so think of all of us living in a conjecting congested town and we want to optimally satisfy the

needs of all people you want to get from one place to another as fast as you can but because we all pay taxes we want to

invest in our infrastructure at minimum in order to maximize than the goals of

everyone who lives within your network so natural selection we argue has done

something similar and that hypothesis is that these quarter power exponents

reflect the constraints have how organisms optimally supply resources through these networks to supply their

metabolic machinery in particular natural selections strong natural

selection optimize biological networks these networks maximally supply resources from

the environment to all metabolizing sounds but yet minimize the cost in

terms of resistance in terms of transport time of the transport through the networks and how does an optimal

network scale as you grow from baby to

an adult the total number of cells in your body increases as mass to the power1 that is you double your size you

double the number of cells that you have but in a big network you need more time

to deliver resources because the network can only supply an optimal Network can only supply resources at mass to the

three-fourths rate a demand is potentially greater than the supply and

because of which you have to turn down your metabolism in order for the organism to function and I can give you

a quick simple analogy to maybe prove my point so let's think about the metabolic

potential of a mammalian cell it's this right incredibly fast

can run at high speed and if you're a shrew that's probably close to what's

real now let's take that same cell cell in quotes and put it into a big mammal

you're not going to be running very fast right you're gonna have to idle quite a bit but your time is slowed because

you're part of a larger network now that same cell but placed within a network

with few limits open highway do we have

proof that in general this networks can strain how fast metabolism how fast life

runs so here's an interesting experiment that has been done this is the metabolic

rate per cell that is the total amount of energy it takes then to we maintain a given cell or a given

volume mass as you increase body mass

normal living organisms then metabolism decreases but in these red cells here

these are cells then there are grown in the laboratory that is their sounds taken from these organisms of a given

size and grown in a petri dish in the laboratory and one of the first things that happens when you take a cell then

out of a out of an elephant or a larger mammal is that the metabolic rate of

cells increase so cells raise in the laboratory free from the network

increase their metabolism and their metabolic rate then is approximately

flat and it intersects the real world line here and that size is the size of

about a shrew the smallest mammal okay so this is consistent with the

prediction that the constraints then of the network limits the metabolic potential of cells so there's a shrew

sitting right there probably flexing energy as fast as possible from the Mahlon cell okay so variation in scaling

of biological rates and times is also constrained by what we call constants of life and this is the last insight that

I'd like to pass along and so I'm gonna give you a few different examples but I'm gonna give you one example in fact

something that we use quite a bit in our in our current research and we're to

focus on the leaf diversity leaves leaves on plants right leaves are really

cool because they not only come in all these different shapes what you know yes

different colors are green but leaves are found obviously in a lot of

different angiosperms and gymnosperms all across the globe and ultimately leaves are responsible for how much

carbon then comes into ecosystems but how much sunlight then the energy from sunlight is ultimately passed along to

then fuel the biosphere so leaf diversity leaves are pretty interesting

because if we look at the I've span men of different leaves I should say that these are little

cocktail swords so this is the ecologist in the field marking individual plants

and study van setting them their life cycles but also monitoring how long these different than leaves of in this

case desert annuals then live in desert annuals their life cycles are timed to

these short little durations of rainfall that occurs these plants grow up in size

make use of a little bit of ephemeral rain and then once the dryness of the desert sets back in they quickly then

die but then we produce before doing so these leaves last on the timescale of a

few days two weeks and in starting this work started to realize well leaves

there's some variation in leaf span but actually there's an enormous variation in how long a given leaf can live so

here's an R acharya tree leaves on our acharya actually can live on the order of about 25 years and it's only been on

the time scale of about a decade or so that research in terms of how long leaves live or plants live has really

started to take off in fact we don't really know much about how long plants live especially some very interesting

ones and probably the longest live leaf is actually from this plant so this

isn't a real win Chia grows in the deserts of Namibia when it germinates it

basically produces just a few leaves puts them out and looks like it's vomiting this green mass looks quite

disheveled but this is the normal state of well which iya these leaves can live

on the order of about a thousand years

so let's think of a leaf as a fundamental metabolic unit again a fundamental unit then responsible for

fixing energy from the Sun and powering then our biosphere so again leaves

dominate carbon water and nutrient fluxes aterrestrials Brooklyn I tell you

is I'm gonna strip away this thin veneer on the outside of leaf and peer in because underneath

the greenness then a belief is a wonderful and beautiful network and this

network and the various traits of leaves associated with the flux of energy and matter are honed to match the local

environment so this is an aspen leaf stripped away of everything on the

outside to reveal the network itself so

biology is a network that network then is responsible for saying all of the

growth or production that occurs within the tropical forest ultimately through leaves through these networks and so

part of the work in collaboration with the ad vendor is that we have been sampling different leaves in many

different environments here we are working with along an elevational gradient in the Andes of Peru going from

the Amazon to tree line to understand the diversity of how plants function and

one of the questions is how can we understand the diversity of branching of both trees but also within these

networks of leaves because we think these networks inform us in terms of how

these forests not only function but what will happen in the future with climate change so can we predict how climate

influences the Vinay shinned diversity that we see in these leaves and so these venation networks are

actually quite beautiful so I'm showing you several different examples several different species and if you look

closely you can actually start to tell differences between species in terms of their different networks

so these diversity this diversity of leaf leaves that we see can be

characterized but what we call the leaf economic spectrum okay so we can

collapse all of the diversity of leaf form and function along this economic spectrum and so the spectrum consists of

how much carbon it costs to build a leaf how long it takes to pay back the cost

of building that leaf but also the lifespan of a leaf and so leaves can be

kind of anchored on two ends of the spectrum we can have leaves that cost

relatively little in terms of creating that is there it's a cheap leaf but

these cheap leaves tend to live very short amount of time and the return rate

how much time it takes to pay back the cost of creating that leaf is a short

amount of time so let's then compare that with the opposite end where we have leaves that live a long time

cost a lot of carbon to make and the return then rate right is also scaled in

accordance and in general we have leaves that either high carbon cost long life low carbon return rate or low carbon

cost short let live lives and high carbon return rates and if we measure

many different attributes of leaves such as how much nitrogen is in them how much carbon that is in them how long they

live how fast the rate of photosynthesis how fast they take up carbon then from the atmosphere and then we plot our

predicted relationships according to this fast slow continuum based on their

networks we can begin to describe these different variations in biological time

of leaves and if I were to compress all of this down into a single axis we have

slow leaves that live a relatively long life and fast leaves that live a relatively short life you can tell that

by looking at their networks so effectively we have

leaves that are that James Dean of life live fast and die young and leaves that

live slowly and steady but ultimately at the end of the day end up making up the

difference and what's absolutely remarkable about the diversity of leaves

across the planet is that for all leaves it takes approximately four grams of

carbon that's assimilated per 1 gram of carbon invested in the leaf so over the

lifespan of a short-lived leaf or a long-lived leaf all leaves are

approximately assimilating 4 grams of carbon for every 1 gram invested in a

leaf a constant why is this approximate

constant why is it 4 grams for every 1 gram invested in making a leaf well we

don't know but it's clear that you can take those 4 grams at which a leaf is

gonna then assimilate over its lifespan and pack it all in in a short time or spread it all out in a long period of

time but it's not just leaves that show this so I'm showing you a plot of the

total number of heartbeats per lifetime in a mammal here's its body size going

from small organisms here's a hamster in a wrap up to large body sizes and so if

you go through and calculate the total amount of life lived in this case in terms of the total number of heartbeats

you come up with the answer 7.3 plus or minus five point six times ten to the

eighth it's about a billion you all have a billion heartbeats I hope you're using

them wisely and those who are astute quantitatively will probably realize

I've already used my billion heartbeats don't worry there is some variation in

biology right there does appear to be some variance but in general if you go

from a small mammal to a large mammal the number of heartbeats is about the

same just like in leaves but obviously no beating heart

so energy of life is constant across scale so the amount of energy flux per

unit mass is similar during its lifetime a mouse flux is about a similar amount

of energy per unit mass as an elephant so now spinning away at an elephant

slowly spending its metabolic capital it turns out that it's about to support a

given amount of mass it's about 8 times 10 to the 5th kilojoules per kilogram so

8 times 10 to the 5th kilojoules per kilogram kilogram in plants and in

animals why this number why an approximate constant we don't know so

maybe we should step back and realize that other people have realized this too so if we were to quote Shakespeare

pleasure and action make the hours seem short so slow down enjoy it

so to summarize I've offered you five different insights a scaling primer I've

given you some evidence that biological rates scale with changes in signs that

biological timescale I've focused on the importance of networks in biology and

that networks in biology seem to underlie the variation of biological times that we see but

ultimately these various variation in the scaling of biological rates and times are also constrained by these

constants of life that we really don't understand

so there's biological time tick at a constant rate well the answer appears to

be known lives perception of time is different than geologic time but

biological time does have approximate constants and we can reveal then these

constants via scaling so to conclude what drives barrel age

variation in biological time variation scaling of biological rates and times are ultimately controlled by the

geometry of vascular networks that appeared to reflect these generalities of life's design and these approximate

universal constraints on the total amount of energy that can be fluxed per mass per lifespan so to go back to the

oldest known human approximately 122 years and to go back to the longevity

website are we going to be able to extend human lifespan possibly but I

think these deeper underlying biological patterns are telling us something very important not only about the quality of

human life but in terms of not only bettering the human condition and if I

were going to use one last quote the quote Shakespeare I've never known so

young a body was so old ahead and so with that there are many folks who have

participated in this work and it inspired me wonderful collaborators as well as different funding sources and

different institutional support and so from with that thank you for your time and your interest and I'm happy to take

any questions [Applause]

just a thought and I'm not a biologist so this could be a complete rubbish and when you were talking about the fetus

and the rate at which the fetus grows within the mum you said they grew at the mum's biological time rate and but when

it's born it starts to take on its rate as it grows and the obviously a fetus it

for most people is something they want inside them a tumor isn't yes so when many tumors grow they grow up

vastly accelerated rates compared with the rest of your body yes why is that is that network control so the question is

when a fetus is growing in your body that's obviously something that you want that is a growth that you want to have

growing in your body but also it is controlled right so mom is controlling the rate of growth the metabolism is

going is the rate of mom but it actually turns out that one of the hallmarks of cancer is that within a tumor

effectively a cancer cell is a cell within the viewpoint of this theory is a

cell that forgets that it's part of a network and cancer cells it turns out

tend to cluster their metabolism around than the metabolic rate of what you

would expect than for a cell of a shrew and another hallmark of cancer is the

redirection of vascular supply networks or disappea to support the energetic

demands then of a growing cancer but those individual cells though likely are not aware that there are parts of a

growing and growing tumor in fact another reason why cancer can be so disastrous is that the ins the inside

then of a tumor becomes necrotic okay because a lot of those cells on the inside are not getting the supply route

that they need so it could very well be that cancer itself at least some forms

of cancer are reflecting them this trade-off of cells for getting the depart and

larger hole a collective hole and thanks

for the fascinating took I was thinking you didn't talk too much about temperature and its impact on metabolic

rates often used to explain why for example creatures in optic regions grow

really slowly and so does that not swear off any of the constants that you were

talking about and also the people who live in hotter places presumably have a

lower life expectancy or people that do more exercise alright so a lot of

different questions then in there Bell I'll take the first one we'll see one get to the next one the later ones

afterwards so that your question first was on temperature and and why I didn't

talk about the importance of temperature and so you would expect maybe temperature to be involved in here

because and if you take say a given plant and you put it then in the

refrigerator and of course give it enough live lights so it can grow but the cold then temperatures tend to slow

than metabolism in warmer environments you would expect metabolism to increase

just with just basic temperature kinetics now mammals we like to keep a

constant homeostatic than temperature in order to maintain a very high metabolism and in general actually this work

everything that I presented there's a whole temperature component of it we can take these equations and put in

temperature in this in fact when we put in temperature it improves our different predictions so yes in general in colder

than places you would expect then metabolism to be slowed which could then also impact on different life histories

in terms of longevity than of things as well and so the temperature component is actually very important other a

theoretical component but I didn't have time to go into the details but if you were a quick you notice that I showed

one plot where we standardized the growth rates of everything we had to standardize the temperature at which

their metabolism is running so and you had another question associated with

what we would expect then for people growing in hotter environments um whether or not we would expect

differences in their physiology or diseases to be different is that right right um would do hot right speed-up if

we're in a hotter place and therefore does a lifespan DK today the price for

that no it's a great question and the quick answers that we don't know but I do know one of my colleagues at the

University of Arizona he's an anthropologist but he's a biological anthropologist and he does a lot of

putting people on treadmills to really land changing their body temperatures putting hot environments and cold

environments as researchers I should inspire from a lot of these scaling that ideas and so he's actively working men

on that so I don't have a quick answer for you but it's a good it's the type then you know this sort of work then

brings a different light to these sorts of questions yeah thank you for a really

nice look I really enjoyed it I was wondering if in all the yellow metric regressions that you have shown today

when there's deviances either positive or negative if you can if you can make

predictions about whether those species may be likely to be endangered or become

invasive if they are under higher or lower constrains okay so they're a few

different questions there and so so the first having to do with the fact that because this these plots are usually on

logarithmic plots right call them bought bought plots that we still have quite a bit of residual variation so in the case

here okay we actually see that there's quite a bit of residual variation that amongst this line does that residual

variation actually means something important biologically right that it can't be used you know to inform kind of

other biological questions and the quick answer that both is yes okay what we tend to find is that this residual

variation is due to things like temperature but also due to the relative nutrients status

okay or differences in life history of different organisms so we actually find

that there's a lot of biology then within this residual variation

so once we control for the all-pervasive influence of size and then temperature

we can then begin to look at deviations then from the mean response as an

indication of what other factors in biology are important now in terms of how these relationships can influence

conservation so if you think about an animal major small to large in terms of

recovery times how long then it's going to take for a small animal versus a large animal then to recover larger

animals need more time for their population densities than to recover excellent example of things like whales

and whale recovery how long it's taken us to recover populations than of whales but it also means that for larger

animals that any sort of local extinction and reduction than the population densities it's going to take

us much longer to recover them those populations and another thing that we're working on actually within yet vendors

lab is that we're using these different scaling relationships to then understand

how over the course of human history one of the biological signatures of the Anthropocene is a gradual reduction in

the maximum sizes of animals okay so gradually we've killed off the megafauna and increasingly we're

reducing the population densities of larger and larger animals and because of which in terms of how long it will take

to recover them those population densities it's going to be quite longer which is going to require more intensive

but also many different lifespans of humans in order to make sure and maintain a conservation effort hi umm

you put a lot of your points with regard to scaling in the context of quite

complex multicellular organisms now you touched on protests quickly but yes there's obviously a massive diversity

single supply single so organism level how do these points and carry over to

those sort of contexts and particularly in the context where you get so pseudo

multicellularity arising like in slime molds and things yeah so then the questions is focused on

what about metabolic rates scaling within you know cells in particular bacteria and some of the earliest of

life this is a very much an active and contentious area in the literature right now one thing that appears to be the

case is that once we get into you know cells there may be an evolutionary

signal where we see these scaling relationships begin to congeal okay and

some of the more recently derived unicellular clades but also leading into

multicellularity so by the time we get to multicellular do we start to see these approximate 3 for scaling

relationships and for some of these you know cells especially if we go of the older than clades what we tend to find

is that these scaling relationships may not be as well behaved or Chara's characterized okay which is maybe what

we would expect okay when the timing of natural selection and to effectively

start operating on these internal vascular networks a good question yes

Tim so how far away can you get from the lines of you're thinking about visit

you're sort of can you get something that's incredibly slow in terms of you know it's sort of that or incredibly

bored well for years it is I'm wondering if you've identified the upper limit but yeah go above but actually deviation can

push things down way below yeah so it's perhaps not surprising that there is residual variation about this line

because I think that's biology that's natural selection trying then to break than these various different constraints

and depending on the local environment maybe you can get away okay was not strictly obeying some of these different

principles and actually one of my postdocs who's now in France one thing these really interested is in crop

plants in particular using artificial selection to try to answer these sorts of questions right so when we

artificially then select for increased production increased growth rate effectively do you basically break the

scaling relationship and don't want to give everything away

but it looks as if many of these fundamental scaling relationships are

still upheld but in order to increase production you have to basically

manicure the environment to become effectively perfect okay no competitors

no disease resource input effectively you have to increase the amount of

energy from human societies in order to support okay these different crop plants that in no

way if you allowed them then to escape into the wild would they ever last so

excellent question yeah in the back um

my understanding is that 300 million years ago they were the atmosphere was much richer in oxygen and therefore we

had much larger you know basically dinosaurs and everything like that and

so that's obviously that the oxygen levels not been constant over time and also the sea has maybe twelve percent

more oxygen in it and therefore you can have large animals in the sea because also the buoyancy of the water will

support larger animals so is a is oxygen err and also affected so I think the

quick answer there the question is yes all right gotcha oxygen concentrations appear to be quite important and it

appears to be correlated with maximum sizes that were around some good natural history examples actually come from

insects right so insects have similar kind of hierarchical branching tubes

right and they require them the movement then of muscles and were then to

basically exchange then air from the outside then to the inside to effectively pump than the atmosphere

from the outside to the inside and oxygen is central then to aerobic

respiration and many different organisms and we find the emergence of these really large insects in particular in

time very high oxygen concentrations and so some arguments have been that these high

oxygen concentrations have have enabled larger and larger body sizes than to to

evolve which then suggests then that because metabolic rates have to be

turned down so low as you increase that in size that if you can increase oxygen concentrations maybe you can get away

then with increasing the efficiency then of supply and supporting larger and larger body sizes but in many ways this

is still kind of I know basically back at the envelope calculations and ideas

but the concordance them between oxygen levels in the past and times in which we

saw these very large organisms and particularly insects seems to support them yeah I studied time in human

consciousness and I've become aware that you know animals have their sense of

time their length of memory or they regard as a long time or a short time I was brought up on a farm so I sort of

watched the animals and what they expected and what they remembered and so on do the many-sided researches of your

Institute consider consciousness of time consciousness of time in animals well

it's an intriguing question the quick answer is that within at least my

department a lot of my different colleagues we haven't started to consider consciousness of time but just

as an additive if I think back in my childhood and I think back about the

passage of time and my mother would say that you know if you save up a given amount you know if your allowance you

know in the end you can buy something really nice that you would like and you know that x ban was on the you know time

span of about a year oh my goodness to me that was forever right waiting forever now a year passes like that now

does that inform us about consciousness and our perception biological time than

intersex I'm not sure but I think that in talking then with people from

different disciplines in terms of how we can potentially merge you know these

different studies of time in terms of the perception of time I think would be fascinating oh thank you yeah

my RV permitted another one please a few months ago here at the Oxford

Martin we heard a lecture about the deep sea in terms of the organisms that actually live and survive a couple of

miles down in deep sea trenches and the guy if I remember rightly said these were very very ancient they never see

the Sun they don't get their power from the Sun they get it from the chemical reactions under the sea now that would

be a very very interesting colony to study to see if that broke this rule wouldn't it yes it would all right so

you're talking about the deep-sea vent organisms these are ecosystems that are energetically run on a completely dead

different sets of biochemical reactions and their energy ultimately comes from geothermal power within the earth

I know of no detailed study trying to put those sorts of organisms on some of

these different relationships part of the issue is that you know once you you can't take these organisms in the deep

sea and bring them up you know to study in our lab because you know they disintegrate and explode and so on because the difference is in pressure

and so it's it's quite hard to study their physiology you know other than taking tissue samples and so on but yeah

I would be fascinating yeah absolutely fascinating thank you Brian a

fascinating lecture I'd like to turn to the point about at the end about these constants that emerge and what your

hypotheses are of work where what these constants mean is it some aspect of

biochemical machinery have just so much wear and tear you can run it faster when it's slow but there's so many

oscillations or right a heart beats Mecca McMahon Michael Isabel you can run in a machine right so I was expecting

this this question probably from you yet vendor so why why these approximate

constants well I think ultimately it's entropy right and so life you know with enough

time does break down and in order to maintain approximate homeostasis in

order to maintain the metabolic machinery in a state where not only resources are being delivered close to the maximal rates but then also

that all the biochemistry associated with growth and biosynthesis is

maintained so I can understand why is this interplay of trying to maintain an

internal homeostasis but yet at the same time having the constraints of entropy that with time things cannot last that

is an item why these exact numbers I don't know I have no idea and I think

that they would you know form a very nice focal point to organize a lot of

the biology that we study yeah

Great Salt Bryan thank you um if we discover life on other planets do you

think it'll obey these constraints well I was gonna be flippant um with the

deep-sea question and but it decided to rain back but since you've given me permission now to do so so what if we

did discover life on another planet okay what if we did where if we were able to

study their physiology right so I would predict that these constraints of taking

in resources from the environment converting them within a body in order to do work that the principle of net of

natural selection for these sort of replication and limiting resources is likely Universal in the truest sense of

the word so if you have competition limiting resources I would think there would be a keen bit of selection to

optimize resource uptake and I wouldn't be surprised if quarter power scaling rules would be the result and I've

argued actually to astrobiologists that if they by chance ever got a chance to

study life that they should look there for these sorts of signatures now if there was only a quote-unquote quarter

power signature that you could scan the stars with no maybe we could increase the speed at which we search for life

but yeah so but that's going way out on a limb so wait

it seems a suitably galactic points to finish it up so thank you Brian follow

that inspiring broad-ranging talk as I as I really texture you tis with so I'd like you all

to join them thank Brian for [Applause]

you