Peopling the earth

it's important to develop a sense of perspective as we consider human history because so much prehistory has happened before we started writing things down and Homo sapiens modern human beings are just the latest link in a chain that stretches back about 5 million years we're not going to start there but I did want to talk about this idea of the home in a day this is the family that includes human beings now a min a day means human like you know the family of the human like and it is further divided into the ha min in a day and the panga day and this goes off to the genus Pongo which is orangutan and then this subfamily divides into two tribes these two sub tribes are goralina and hominid I think you can kind of figure out where goralina goes to it goes to gorillas and hominid knee splits again into the genus pan and the genus Homo pan is the genus that would eventually come to include chimpanzees and bonobos and Homo is Latin for human being and this is the genus that would come to encompass us but what I want to talk about today is this elbow this evolutionary elbow and how we got from hominid knee to the genus Homo to what we are today which is Homo sapiens the thinking man thinking human being and this this branch here the last time we had a common ancestor with what would eventually become chimpanzees was about 5 million years ago and at that time 5 million years ago the creatures that would one day become human beings were arboreal simians they were ape-like or monkey like creatures that lived in trees paleontologists have reconstructed their diets they ate mostly fruit and they largely were quadrupeds they got around on four legs or they they knuckle walked similarly to how gorillas and chimpanzees today rest some of their body weight on their knuckles as they locomote as they move around at some point though the arboreal simians these tree dwelling creatures came down from the trees and began walking on the ground and in fact not just walking on four legs but eventually walking on two this is called bipedalism from by meaning to and ped meaning feet now more research about ancient hominins that's this group here indicates that their diets didn't especially change when they came down from the trees by studying the dental remains of early hominins we can determine that they ate a lot of nuts and seeds and fruits so why do they have to come down from the trees well there's this idea called the aridity or savannah hypothesis and aridity is just another fancy way of saying DRI that postulates that the number of trees just kind of went away that there was a climate event or a you know a change in the climate that led to trees being less prevalent in the part of Africa where these human ancestors were to be found so proto humanity leaves the trees and begins walking upright and one of the most notable examples of this is Australopithecus afarensis Australia in southern Pittacus meaning ape afar for the afar region in what is today Ethiopia which is where the original specimen was was found now the most famous Australopithecus afarensis as a woman named Lucy who was found in 1974 and is supposed to be about three million years old now to further the story of hominin development I'd like to tell you the story of three skulls so here we have three different specimens from three different periods in history so all the way over here on the Left we have paren through Paseo PICUs which means you know near human of Ethiopia that's where the specimen was found this specimen might be from 2.5 million years ago this here is homo erectus upright human and these hominids were from about 2 million years ago to about 700,000 years ago and this is Homo sapiens this is a human skull and Homo sapiens dates to about a hundred and thirty thousand years ago now I want to tell you about the differences between these skulls and what they can tell us about human development now per anthroposophy öbecause was a bipedal hominid it walked upright on two feet but we can see from the shape of its skull that it had a very different diet than Homo sapiens I'll explain why this thing up here this like ridge up top this is called a sagittal crest and the reason this crest exists is because it's where this muscle this is the temporalis muscle was anchored the temporalis muscle is one of a couple of muscles in the human face that's used for chewing the other one is the masseter it's around here so what sort of diet would / anthropophaga civ had if it needed to have an enormous skull structure to anchor this equally huge utterly swole temporalis muscle well it ate really tough food right it required a lot of chewing and it's not like human beings don't have a temporalis muscle we do it's over here it's why if you've you know if you've ever gotten like a headache for after chewing gum all day that's actually muscle pain from a strange temporalis muscle we we have that muscle we also have the mass that are right here but I want to illustrate with these skulls the difference between this diet this diet and this diet because you can see in this in this Homo erectus skull here we don't have that sagittal crest anymore you might have like a slight sagittal Ridge from where the the skull plates come together but it's no longer for the purpose of anchoring that that muscle so something happened between / anthropos Co Pacus and Homo erectus and we know what that thing is we was a couple things tools and fire Homo erectus was a hominid species that learned how to create stone tools and play with fire and when I say play with fire I mean really use fire because I want you about why is fire important number one calories you can make a starchy root vegetable more caloric by heating it up and converting some of those starches into edible sugars if you think about like a cassava root or a raw potato right like cooking those with fire makes them edible so if you control fire you're less likely to starve to death you can get more food out of less number two it kills parasites if you're eating raw meat if you're on a hunting trip and you kill a deer or a boar that thing could have worms in it you don't even know right but putting you know roasting that boar instead or cutting off pieces of meat and and roasting or grilling them is going to kill the parasites inside most the time so this also helps to ensure a healthier population number three in the so little obvious it keeps you warm and safe at night fire will keep wild animals away and you can not you know freeze to death and that brings us to Homo sapiens who has tools who has fire and who has yet another thing which is language and it's with those three things in concert that Homo sapiens was able to accomplish what it accomplished this is a map of migrations that hominins and Homo sapiens made throughout the years so the earliest Homo sapiens had been spreading on the African continent for about 500,000 years but it wasn't until about a hundred thousand years ago that they crossed into Eurasia and started spreading into Europe and into Asia and to the Indian subcontinent we're skirting most of what is today Russia and China because at this point it was just completely covered in ice and so human beings made it to the Indian subcontinent about 70,000 years ago and then down through Southeast Asia and eventually making their way to Australia by about 50,000 years ago to new Guinea my 30,000 years ago and eventually through Micronesia about 1,500 years ago making our way all the way to New Zealand here what is today New Zealand this is a when we think about this map this is a map without countries these are just land masses I'm just using the names of the nations that occupy these land masses today just for the sake of convenience about 25,000 years ago our human ancestors began making their way up into the interior of the Eurasian steppe and then crossing what was either an iced over land bridge or using tiny boats to make their way across the Bering Strait into North America this would have been about 15,000 years ago and then variously making their way into the North American interior and again hugging the coastline and bouncing their way down rapidly expanding into Central and South America and this would have happened around 15 14,000 years ago this was like a rapid expansion of just people bouncing down the coast and exploring now this is a map of Homo sapiens migration in pink but there were also other hominids that were living on the planet and this blue represents Neanderthal man which is another another Homo genus species right so if red is Homo sapiens then blue is Homo neanderthalensis now just because Homo sapiens was the only hominid species to survive into the modern age that doesn't mean homo sapiens is best that just means we were really dang lucky now we're not certain why it is that spreading throughout the African continent around 200,000 years ago and then groups of humans leaving the African continent a hundred thousand years ago why that took place we're not sure but but scientists and historians surmise that it has something to do with resource scarcity similar to the aridity hypothesis that took our hominin ancestors down from the trees and onto the grassland where they had to stand upright it seems likely that some other kind of reefs course disaster forced human beings forced these early human beings out of their comfort zone to look for food elsewhere so how'd they do it was a combination of ingenuity luck tools and language as hominid brains increased in size early humans acquired the ability to communicate with each other and form complex social groups you can't organize a group of 15 people to build a raft with you and sail to Australia or skirt the coastline of the Americas without some method of communication sure the ancestors of lemurs which today are only found on Madagascar certainly those ancestral lemurs made it to Madagascar without language and without tools but paleontologists surmise that they got there via this thing called random rafting events if you can imagine a couple of lemurs caught in a storm clinging to a tree branch that gets swept out to sea that's how they cross the Strait of Mozambique a lot of scientists think but in order to journey with a small band of human beings island hopping in this way takes intentionality and it takes a command of the environment around you and it takes communication and cooperation walking upright wielding fire shaping stone and wood into tools these developments enabled human beings to people the earth reaching pretty much everywhere that wasn't a polar region now what they do once they got there and settled down well that's a story for another time