(upbeat music) - [voiceover] have youever wondered about your human ancestorsthat lived more than one million years ago? you may have imagesof ape-like people that sheltered incaves and used clubs. a special group of scientists,called paleoanthropologists, use clues from theprehistoric record to uncover the mysteries of what earlyhumans were really like.
the work of these scientistshelps us understand what it means to behuman and how we evolved to the unique speciesthat we are today. in this episode, we'llmeet paleoanthropologist briana pobiner to learnmore about early human life by looking at what was on themenu one million years ago. - hi, thanks for joining us. i'm maggy benson, host ofsmithsonian science how. we have a really awesomeshow planned for you today,
but before we get started iwant to ask you a question. you can respond usingthe poll that appears to the right ofyour video screen. what makes humans differentfrom other animal species? is it talking, walkingupright, using tools, thinking abstractly,or having big brains? take a moment to think about it and put your answer inthe window that appears all right, it looks like theanswers are still coming in,
so before we go to theresults, i want to introduce our special guest today. today we have with uspaleoanthropologist from smithsonian's nationalmuseum of natural history, dr. briana pobiner. thank you so much for beinghere with us today, briana. - you're welcome. - right now, we basicallyhave three answers coming in that are top, walkingupright, thinking abstractly,
and using tools are allanswers that people are responding thatmake humans unique. what do you think about that? - i think in some ways allof those answers are correct, but really it's sortof an all of the above. it's the whole package thatmakes us uniquely human. we have these amazinglylarge brains, we have very sophisticated language andtechnology, and we walk upright on two legs which isfairly unique among animals.
- [maggy] i have to askyou, what about chimpanzees? i know that we're reallysimilar to them in all of our behavior, so does thatmake us really that unique? - we're not only similar tochimpanzees in our behavior, but the way that we lookand also our genetics. we are 98.8% geneticallysimilar to chimpanzees. they do a lot of the thingsthat we do, they walk upright from time to time, theyuse tools, they have fairly sophisticated communication,but actually humans
and chimpanzees sharea common ancestor that lived about six orseven million years ago. so we've had quite a long time to evolve on thoseseparate paths. if we have 3.2 billionbase pairs in our genome, a 1.2% difference is maybe35 million differences. - [maggy] oh my god, so only1.2% of our genetic code is different, but it reallymakes us uniquely human. - it does, thatmakes us who we are.
- i guess 6.7 millionyears of evolution too. - that's right, that'squite a long time. - can you tell us whata paleoanthropologist is and what you do tostudy human evolution? - sure. a paleoanthropologistis essentially a scientist who's interested in earlyhumans, what they did, how they lived, what theyate, all about their biology and behavior. sopaleoanthropologists usually use three lines of evidence tolook at early human lifestyles.
we use the fossils of theearly humans themselves. we use animals' bones orfossils of animals that lived at the same time asthose early humans. we can tell somethingabout environments from those animals, possiblysomething about diet. we can also use thearchaeological record. stone tools, pottery, anykind of, basically anything that was left behindthat early humans made. - interesting, it sounds likethere are a lot of different
puzzle pieces across thosethree lines of evidence. - there are and it'sreally neat to try to fit those puzzle pieces together. we're never gonna haveevery single piece, but really trying to makesense of the evidence that we have. - can you show us something,i see evidence on the table here, can you show ussomething that you brought? - sure, i brought the exactreplica of a skull of probably
my favorite species on humanfamily tree, homo erectus. one of the things that makeshomo erectus so special is that it started to incorporate alot more meat into its diet. i'm really interested in meateating and early human diets. by about 1.8, 1.9 millionyears ago, when this species evolved, it started to eatmore meat and more marrow and other thingsfrom large animals. we can see that reflectedin the shape of its skull. in comparison to a species likeaustralopithecus afarensis,
which lived much earlierback to almost 3.9 million years ago, the slope ofthe face is much different. a lot of the faceof australopithecus used for chewing, butthen once early humans started using stone toolsto butcher meat they could basically process foodoutside of their mouths. so our teeth got smaller,but our brains got bigger. - interesting. so whatdid we eat before we started eating meat?
so what did maybe afarensis eat? - even back to theearliest human ancestors, back to six or seven millionyears ago, we probably had a very omnivorous diet,so eating plants and animals. eating things like fruit andleaves and berries and probably small animals, maybe insects,lizards, eggs, all sorts of things, kind of anythingwe could get our hands on. - you mention that therewere other species, other than afarensisand homo erectus.
how many humanspecies were there? - the family tree, our familytree is pretty bushy actually. it's very diverse, therewere maybe somewhere between 18 and 20 specieson our family tree. at any one time, there wereoften several species living at the same time. it's fairly uniqueto be a modern human and to be the onlyspecies left standing. you can see right there, kindof on the top of the tree.
- [maggy] did all of theseanimals live at the same time? - [briana] many of themdid, you can see where some of them overlap andin fact, modern humans, our time span overlaps withat least three different other early human species. - [maggy] interesting,so the early humans that you study,where did they live? - there are a coupleplaces that i work. one site that i amcurrently doing research at
is called olorgesailie, it'sa site in southern kenya, in the southernkenya rift valley. we actually have a beautifulphoto of olorgesailie right in back of us, this iswhat the landscape looks like. it's very eroded but ithink it's quite beautiful. we're working at olorgesailieunder the direction of dr. rick potts, who's alsoa paleoanthropologist here at the natural history museum. - [maggy] what kind ofthings do you look at
at olorgesailie? - [briana] i'm particularlyinterested in looking at the animal bones there. i've actually broughtone with me today. this is a rib of somesort of large animal, maybe about a zebrasize, that's about a million years old. - [maggy] wow, that'sso interesting. so you may find someof these fossil bones
here at your fieldsite in olorgesailie. what else do you findat the field site here? - we find lots of differenttypes of evidence. it really takes a team tobe able to put together the pieces of thisprehistoric puzzle. we have archaeologistswho study the stone tools. we have paleoanthropologistsor physical anthropologists who study the actualfossils of early humans. we have paleontologists thatstudy the animal bone fossils.
but geologists are alsokey, so these are scientists that help us figureout how old the fossils and artifacts were andalso help us reconstruct the types of landscapesand environments that early humans lived in. - wow, that'sreally interesting. we already have astudent question for you. are you ready to take it? - sure.
- this one comesfrom amy from acacia. she wants to know whois our closest relative? - who's our closest relative?that's a good question. that's sort of amillion dollar question. right now, based onavailable evidence, we think that probably our directancestor is a species called homo heidelbergensis. this species lived inafrica and in asia, i'm sorry and in europe,
that dating back toabout 800,000 years ago. populations of this speciesin africa evolved eventually into our species, modernhumans or homo sapiens, about 200,000 years ago. the populations in europeevolved into neanderthals and neanderthals are ourclosest extinct relatives. - [maggy] wow, interesting. we have anotherquestion for you. this one comes from ruth.
ruth wants to know isthere any way to know what we will evolve into? - wow, that's afascinating question. a lot of that's hard to predict. the way that evolutionworks is that changes often happen or areselected for in response to a particular selectivepressure in response to a particularenvironment or challenge. not knowing what thosechallenges will be
in the future, it's a littlehard to predict how our evolutionary trajectoryis going to proceed. - great. i want to get backto this bone that you brought. that was recoveredfrom olorgesailie one you said that looking atmarks on bones is your primary research, what do you lookat when you look at marks? - i'm particularly interestedin trying to figure out who made these marks on bones. some of these marks weremade by early humans
when they used sharp stonetools to butcher animals. some of these markswere made by carnivores when they were basicallyeating their prey and munching on these bones. - [maggy] so, like wesee on the screen here, are those chew marks or what? - [briana] those are greatexamples of cut marks on fossil bones, cut marks arelinear, they're very narrow. they usually have av-shape at the bottom
and they're usually eitheroriented right across the bone or kind of diagonallyacross the bone. in contrast, carnivore toothmarks, especially tooth pits, they're usually round,they're crushed on the bottom of the surface of the mark,and they can sometimes be scattered throughoutthe bone or often sometimes kind of concentrated on placeswhere carnivores have chewed. - [maggy] i want to know howyou actually do the research to be able to understand whatmade that mark on the bone,
because we don't have alooking glass to look back a million years ago. - i would love that. one thing i do is i'm tryingto determine what different carnivore chewingpatterns look like. to do that research, i workat another site in kenya, called ol pejetaconservancy which is a site in central kenya, it'sa modern game reserve. i'm working there togetherwith my colleague,
dr. fire kovarovic fromdurham university in the uk. we are basically looking atkills that lions, leopards, hyenas, differentcarnivores have made to try to determine if we canfigure out what that lion chewing pattern, that leopardchewing pattern looks like. so we go out in thesemodern landscapes, we follow these carnivores aroundand then we pick up their leftovers and study those bones. - is that scary?
you're out on thismodern game reserve with these big carnivores. - not only with thesebig carnivores, these big meat eaters, but elephantsand rhinos and buffalo. it can be a little scary,but we always go out with an armed guard, with anarmed ranger, any time we're out of the car tomake sure that we're safe. - interesting, did youbring any objects here today that show what someof these chew marks
look like on the bones? - i did. here is oneexample of a zebra bone that has some nice chewingdamage from a lion. you can see right herewhere the arrow is, there's basically a bigcarnivore tooth mark back here and over here is all of thisnibbling damage that happened when a lion was chewing totry to get this meat off and ended up chewingpart of the bone. - you've done a great jobhelping us understand what
a chew mark looks like anda bite mark and a cut mark. let's go back to this ribbone that you brought. - i think maybe we shouldask the students what they think that thesemarks were made from. - [briana] that sounds great. - [maggy] wonderful, studentstake a look at this bone and maybe briana'll point outwhat marks we're looking at. what do you think the markson the bone were from? grass impressions, tooth marks,
water staining,or butchery marks? all right, briana, theanswers are coming in and 50% of our students thinkthat they're butchery marks. - i think that's a great answer. really it's the factthat they're quite linear and straight andnarrow that gives away that those are butchery marks. - [maggy] so they're butcherymarks made by stone tools. that means thatearly humans were
using stone tools amillion years ago? - actually early humanswere using stone tools all the way back to about2.6 million years ago. we have very sort of simpletechnology at that point, we basically have simplerocks with flakes that were knocked off of those rocks. not very sophisticated, butthey were really perfect at getting a sharp edgeto be able to slice meat off of bone.
by the time homoerectus came around, there was a big innovationin stone tool technology. this is a hand axe,this is a real hand axe from olorgesailie, thishand axe has a very specific pattern thatthese sharp flakes were taken off around the edge. it's actually a veryefficient way to use your stone tool raw material. - great. we have anotherstudent question.
this one comes fromlong gone daddy. is there any evidence thatparticular diet and nutirents contributed to brain orlanguage development? - that's a good question. actually there is a lotof evidence, or at least a good hypothesis, thateating meat contributed to an increase in brain size. so meat is a great resourcethat has a lot of calories, it has a lot of fat andnutrition, and being able to get
all of that in a smallerpackage versus a lot of leaves or fruit may have enabledour brains to grow bigger. - great, this one comesfrom briana from fis. she wants to know wheredo you take the fossils after you piece them together? all of the fossils stayin the country where they've excavated from,where they've been excavated. all of the fossils fromolorgesailie stay at the national museums of kenya.
they go to the centralmuseum in nairobi. - great. you mentionedthat these stone tools were used for butchery. does that mean that theywere actually hunting with them too or werethey just using them to butcher the animalsand eat the meat after some animal mayhave gotten to it? - that is anothermillion dollar question. we don't have evidencefor hunting technology
in the archaeologicalrecord until about half a million yearsago. you'll notice that's two million yearsafter the evidence for this meat eating started. we think that sometimesactually early humans were coming in after carnivoreswere done with their kills or maybe even chasingthem off and that's how they were getting meatfrom these big animals. - [maggy] were the earlyhumans kind of waiting in
the bushes, waiting for theselions to get off their prey? - it's hard to know, wedon't have evidence for some of that specificbehavior, but we probably, we can infer from wherecut marks are on bones. if the early humans aregetting the really juicy parts of carcasses, it's anindication that they may have been chasing carnivores offof kills or somehow being able to get better access to thebest parts of the animals. - is that primitivescavenging or is it actually
an advance for that timeperiod to be able to be waiting and thenbutchering these animals? - it's funny, i think scavenginggets a really bad rap. i think it's actually afairly sophisticated behavior. you really have to knowyour environment very well, know where thecarnivores tend to hunt, have advanced planning,and very sophisticated communication and groupdynamics and social interaction. i think it's actually a prettyadvanced kind of behavior.
- interesting. eating meatreally was the critical changing point for us to beable to have all of these human unique qualities. - at least it was avery big changing point. there's two other kind of bigshifts in early human diet. one is by about 800,000 yearsago, we have good evidence that humans were usingfire for cooking. then by about 15,000 yearsago, it's kind of late in the record as far as we'reconcerned, we have good
evidence for agricultureand domestication, which is basically growingplants and tending animals for our own food resources. - wonderful, you've done areally great job at explaining to us what a paleoanthropologistdoes, about your fieldwork here in kenya,here in kenya, (laughs) and the evolution ofreally our human diet. let's go to somestudent questions. - sounds good.
- this one comes from louisa. louisa wants to know mightearly humans have gotten the idea of cooking meatfrom scavenging meat from animals caught in wildfires? - that's a really good question. we think there were probablyoccasional wildfires, that lightning strikes orsomething ended up lighting these wildfires, it certainlycould have been from something like that,that's a good idea.
- this questioncomes from haegen. haegen wants to knowwhy were animals from millions of years ago so muchbigger than they are today? - that's actually areally good question. we have really across thewhole world and almost all of our continents, thereare big extinct animals that are no longer around today. i think it's complicated,but there's probably a lot of reasons for that.
- this one comesfrom harold woods. harold woods wants to knowhow many different types of food did we eat beforewe started eating meat? - that's a very good question. we have a lot of types offood we were probably eating that don't preserve, thingslike fruit and leaves and berries, so we canget preserved bones and sometimes even preservedlittle bits of plants, but it's harder to lookreally deep back in the record
and figure out whatwe were eating. - this one comes from scottin fairfax. scott in fairfax wants to know did earlyhumans eat raw meat? - i think the answer is yes. we have meat eating backto about 2.6 million years ago at least, but we don'thave good evidence for cooking until 800,000 years ago. it's possible that we'llfind earlier evidence for cooking, but it looks likeraw meat was being eaten
for a long time. - otto from rapid citywants to know what education do you need to dothis kind of work? - the first thing youneed is a college degree, usually in anthropologybut maybe in biology or geology or even somethinglike chemistry and physics to do some of thosedating techniques. then most people do goon and get a master's and a ph.d.
- briana, what made youinterested in paleoanthropology? - [briana] i admit that i wasnot as interested in science when i was in highschool than i am now. it was really a class that itook in college with a really inspiring professor thatgot me started on the anthropology path and theni went to a field school in south africa andabsolutely fell in love with the discovery and thinkingabout human prehistory and trying to find thosepieces to that puzzle.
- great. we haveanother question. this one comes fromjaclyn. she wants to know do you ever find painting onany of the bones that you find? - interestingly, we do.sometimes we find coloring. so pigments, either redpigments made of ochre or black pigments likemanganese, occasionally we do find staining on those bones. - wow, and you think that isthen two lines of evidence together as one, both the humanartifact and a fossil bone.
- exactly, it's a little bitlater in time so we really don't have the evidence formaking art until a couple hundred thousand yearsago, but we certainly do find marks on stones andbones and certainly caves and things like that. - great, alex has a question. alex wants to know did ourbones get bigger over time? - so our brains got biggerover time and that meant that our skulls had toget bigger over time,
at least that part of our skull. in general, our body sizedid increase over time, so our bones, our wholeskeletons, got gradually bigger over time. - [maggy] and that was reallybecause of meat eating? - [briana] it probablyplayed a big part, yeah. - that's so interesting, i'mlooking here at the models that you have out on thetable, what order did they come in? do you know?
- yeah, so i would actuallyhave to switch these two. the earlier fossils fromaustralopithecus afarensis, leading into the earliestmembers of our genus, the genus homo, so you cansee a little bit of change in the size of the brainand the slope of the face. then once we get past homoerectus to neanderthals, you can see they're muchbigger and actually have a really large brain andvery big brow ridges. - now neanderthals, inthe geologic record,
they're kind ofrecent, aren't they? - they are and actually theyevolved around the same time that modern humans did,about 200,000 years ago. - [maggy] they werefound in north america? - they were found ineurope and in western asia. - [maggy] oh, okay. - actually, modern humanswhen they migrated into europe encountered neanderthals, theywere living in the same place at the same time and weactually know from genetics that
they occasionally interbred,they mated with each other. - great, we have anotherquestion from patrick. patrick wants to know how didearly man learn to make tools? - oh, that's a great question. i'm not sure we'll everanswer that question. it may have been initiallyjust picking up sharp stones and using those as stoneknives that gave the people the idea to actuallymake early stone tools and to manufacture theminstead of to just kind of
go out and collect them,but we really don't know. that's a good question. - wonderful. thisone comes from david. david wants to know whendid the early humans learn to build shelters? - so that's a good question. we have the earliest evidencefor building shelters back to about 400,000 yearsago, at least that's what we can discern in theprehistoric record.
- john b: what is your favoritefossil that you've found? - wow, that's a hardquestion because i love all the fossilsthat i've found. probably some of the fossilsthat i've found where i'm digging up inlayers that are about one and a half millionyears old and i can pick up bones like this cut markedbone and i know that the last person thattouched this lived a million and a half years ago.
wasn't quite like me, butit's really like reaching through the past and touchingevidence of behavior. - [maggy] sounds exhilarating. - [briana] it's amazing. - brian wants to know sincethe tools were made of stone, how hard were they to use? - oh, that's a good question. they actually weren't thathard to use in the sense that you could pick one up,one that had a sharp edge,
and it's not hard to actuallyslice meat off of those bones. tools were also used forpounding for probably processing plants. it was probablyhard to make them, but not as hard to use them. - this one comes fromjonathan. he says besides the brain, did anyother organs change? - well, interestingly, aboutthe same time that we see the brain size increasing,we actually see the size
of our guts and our wholedigestive tract decreasing. those things might berelated, so our brains take up about 2% of our bodyweight, but they take up 20% of our energy and our gutstake up a lot of energy. so potentially with eatingmeat, we didn't need guts as big so they got smallerand brains got bigger. - interesting. in a kindof related question, emma wants to know didsalmonella or any other kind of diseases exist backthen that we have today?
- it's interesting. it'srare but we do have evidence of diseases, there's actuallycancer or bone lesions on a neanderthal rib from tensof thousands of years ago. there's actually a partialskeleton from northern kenya where we know that thiswoman suffered from hypervitaminosis a, probablyactually eating something that had a really highconcentration of vitamin a, which is especiallyconcentrated in liver and actually carnivore liver.
- wow, so you can reallyactually see some of those diets in the fossil record, too. - and diseasessometimes, exactly. - this one comes fromlindsay. lindsay wants to know how do you feel aboutindigenous creation stories? - i think that basicallyhow we became human is a part of what itmeans to be human, but i think that thestories that we have in the cultural contextof how we became human
are also a really importantpart of who we are. - great. this one is kind offunny. sophia wants to know will our pinky toeevolve away? (laughs) - it's funny, actuallyhaving five fingers and toes is a really primitivecondition, in a sense. that goes back really farin our evolutionary history. unless there was really strongselection for some reason for our pinky toes to go away,they're probably gonna stay put. - [maggy] that'sa good question.
- it is a good question. - raymond wants to know isthere any difference in early human bones becoming fossilsas opposed to animal bones? - the process wasprobably the same. a lot of the bones, if youfind human and animal bones in the same layers, theyusually look the same. it's really just the sizeand shape of the bone that lets us know whatkind of animal or human they came from.
- going back to the sizeand the shape of the bone, anthony g. wants to knowhow do you tell what kind of bone it is? is there a spoton the bone that tells you what kind of bone it is? - that's a good question, iactually spend a lot of my time trying to figure out whatbones these fossils are. sometimes on parts of thebones there are very specific shapes, you can see some ofthese curves and ridges here. if you get chunks of bonethat have these shapes,
they're a loteasier to diagnose. sometimes when you havereally little pieces, it's really hard to tell. - so you're really kind oflike a forensic anthropologist, too, that we see oncrime shows like csi? - in a way, trying to put,look at tiny bits of bone and trying to figureout what they are. - thank you so muchfor being here today and teaching us aboutpaleoanthropology,
human evolution, andearly human diets. it's been really enlightening. - [briana] oh,well, thanks a lot. - is there anywhere thatstudents can go to learn more about human evolutionand the work you do? - i would suggestgoing to our website, which is humanorigins.si.edu. if you're on social media,you can follow us on twitter @humanorigins and then youcan also find us on facebook
smithsonian humanorigins program. - thank you so much. - thanks. - thanks again forjoining us today. we're glad that you came. if you missed part of thisbroadcast or want to watch it again, it'll bearchived at qrius.si.edu later tonight. thanks for joining usand see you next time
on smithsonian science how.