History of the Human Evolution

Ok so i wanted to do a thread on my understanding of the history of our human evolution. I've been studying how it happened and trying to put it all together and this is what i have come up with.

So basically about 5 to 8 million years ago, in Africa, lived a common ancestor to humans and gorillas and chimps. The common ancestor's species then broke off into two separate lineages, one ultimately evolving into gorillas and chimps, the other evolving into early humans called hominids, which is the lineage that i have been studying. This common ancestor has been dubbed the missing link, but the scientific community cannot come up with what species that common ancestor actually was.

Next about, about 6 million years ago, from the missing link evolved an African apelike species called Australopithecine, which means southern ape. The two things that set this species apart from the apes was that they had small canine teeth (apes have long canine teeth) and more importantly bi-pedalism, or the ability to walk upright. There were many different species to come from this lineage. The most famous of them is Australopithicus afarensis, which is the species that the australopith specimen Lucy came from. Lucy was a partial skeleton of a female discovered in 1974 in Hadar, Ethiopia. Lucy is said to be 3.4 million years old. Australopithicus afarensis is important because it was the first species to start walking upright. The reason they started walking upright was because they were mostly tree dwellers and climate change in Africa changed the unbroken forests of Africa into grass and scattered woodland. So since the trees were starting to die off they had to come out of the trees to get food. This forced these ape like creatures to evolve and start walking to get food, or they would die off. In the grassland roamed leopards and tigers, which forced Australopithicus afarensis to start running to avoid preys. Now since they were running in the grass to get food, it freed their hands and allowed them to start using tools. The tools were basically just rocks for pounding and crushing rocks and bones. Using tools made them smarter and caused their brains to get bigger. Now multiply doing this for about a million years and it evolved the apes significantly.

These changes evolved the australopithicus genus into homo genus, which was about 2.3 to 2.5 million years ago. The first homo genus was homo habilis. They are noted as the first species of human to begin using tools made out of stone, which means they had evolved and are now smart enough to being able to start making tools out of stone and bone. They used these tools to pound and crush bones and to cut meat out of larger animals. This new meat gave the species better protien, which also helped the evolutionary process. Homo habilis looked a lot different than the genus australopithicus because the had larger brains and smaller teeth. The reasons they evolved like this was the use of tools which made them think more giving them bigger brains, and smaller teeth and that's from their change of diet.

Homo habilis evovled into homo egaster about 1.9 to 1.8 million years ago. homo egaster was stable in the fossil record for about 500,000 years before going extinct. Homo erectus also evolved around this time too. Some major changes that were happening around this time with the evolution of our species was that we learned to control fire by homo egaster about 1.5 million years ago, giving us access to better proteins from cooked foods. Our bodies were developing more complex sweat glands causing body hair loss, and it made us pant less paving the way to learning speech, which happened around 1.2 million years ago. We have found ancient tools from about 1.5 million years ago that have showed how advanced homo erectus had become. There is also evidence showing around this time that we began to care for each other and were part of large groups or tribes.

Homo heidelbergensis developed next and lived from about 600,000 to 200,000 years ago. There brain was about as large as modern day homo sapiens, showing just have far the evolution was coming along. They were also the first species of homo to start burying their dead and hunting showing just how smart humans had evolved too also. There was a group of homo heidelbergensis that migrated out of Africa into Europe later evolving into homo neanderthalensis about 300,000 to 400,000 years ago. The homo heidelbergensis that stayed in Africa later evolved into homo sapiens.

Homo Sapiens evolved around 200,000 years ago. Like the other species of humans living around this time, they gathered in tribes, hunted for food and evolved behaviors that helped them survive in the now rapidly changing climate. By this time humans have developed large brains and light hairless skin. They also now made bows, fished and sewed. Homo sapiens migrated out of Africa into Europe about 40,000 and are said to be the reason homo neanderthalensis is now extinct.

Now i have left out a ton of different species from both homo and australopithicus, i was just trying to get at the big picture of the main events that caused the evolutionary process.

a reply to: taylor73

Sounds about right but there is much that we don't really know and are assuming.

For instance, despite their larger brains, larger bodies, developed culture and tool use, Neanderthals were most likely wiped out by competition with a more vicious Homo Sapiens.

There are also many tool-using animals that have obviously not followed the evolutionary path to cephalisation.

The concept that tool use led to larger brains is actually quite Lamarckian when you begin to try and reason it out.

Physiological changes such as a larger brain must have a selection advantage to be expressed in a population. The mechanism of natural selection is that selection pressures 'thin the herd', i.e: they cause the reduction of population of those carrying the disadvantage. 'Selection pressures' that do not adversely affect population numbers, have no effect upon evolution.

Similarly, in humans we often equate braininess with 'higher' evolutionary progress, but this is implicitly suggesting a direction or goal. Certainly, at some point, our intelligence has become our primary survival trait and as we develop genetic and technological power, we will take control of the evolutionary process, subsuming it to our will. This then equates to an overall goal to evolutionary progress in humans (but perhaps not to other species).

a reply to: taylor73

There are literally hundreds, if not thousands of species in the fossil record that share taxonomic similarities to our modern decedents of our ancestors. And if you take our evolution as a whole, billions.
It is a rather bold move to try and summarize our entire evolution in a post that's about 6 full paragraphs long. But I get your point.

If you really want to get a full picture you would most likely need to start purchasing university caliber text books on physical anthropology, a first year text book will generally give you an idea of some of the more unknown lineages, such as the gorilla.
After start and refine your study, backwards from modern ape population, gorilla, human, gibbon, etc and find the 'fork' in the road.
Recently there have been good findings that those who made it out of Africa mingled, fought, mated, etc with neanderthals more than we thought which put's a bit of a spin on the 'modern' human theory. So, I would concentrate on ape populations before the exit from Africa and see where they split.

a reply to: chr0naut

Hasn't there also been speculation that the development of human speech also gave Homo Sapiens an advantage?

originally posted by: AngryCymraeg
a reply to: chr0naut

Hasn't there also been speculation that the development of human speech also gave Homo Sapiens an advantage?

Definitely, pack hunting would be greatly enhanced by communication. I would class this as applying considerable pressure to those without communication, in competition for food resources.

a reply to: chr0naut
I have heard the theory that Neanderthals were exterminated by the "more agressive" Homo sapiens.
It could have been the other way around.
The Neanderthals may have been highly aggressive toward our kind when the two crossed paths.
We decided that having the camp raided and people snatched away by giant cannibals was unacceptable.
We waged war. With our superior pack hunting and communication skills, we stomped their hairy asses into the annals of history.
Just a thought.

originally posted by: skunkape23
a reply to: chr0naut
I have heard the theory that Neanderthals were exterminated by the "more agressive" Homo sapiens.
It could have been the other way around.
The Neanderthals may have been highly aggressive toward our kind when the two crossed paths.
We decided that having the camp raided and people snatched away by giant cannibals was unacceptable.
We waged war. With our superior pack hunting and communication skills, we stomped their hairy asses into the annals of history.
Just a thought.

Yes, it could have been that way.

Perhaps Asguard vs the Ice Giants

a reply to: chr0naut

Yeah your right about tool use being the only reason that led to bigger brains. From 6 to 2 million years ago walking upright and making simple tools led to brain increase but only slightly. From 2 million to 800,000 ago early hominin species began to spread out around the globe to face new environments and challenges. That, mixed with an increase in body size, led to more brain increase. The most rapid and biggest increase in brain size happened from 800,000 to 200,000 years from climate change. The larger and more complex brains evolved during this time because they need to interact with others and the environment in new and different ways to cope with the changing and unpredictable climate.

Also neanderthals had bigger brains than homo sapiens, but they developed larger visual cortices, so they had to use more brain power to see. They also evolved in Europe and homo sapiens in Africa, so they had different cultures. The homo sapiens were more culturally and socially advanced, the Neanderthals didn't grow socially the way homo sapiens did, which shows that different parts of the brain developed. So basically neanderthals evolved better sight because they focused on individual survival more and they had to see better. They also relied on their brute strength more. We evolved socially and used our communication and numbers to survive and interact with the enviroment, which helped us evolve into smarter humans.

a reply to: strongfp

Could you be more specific on some of the similarities that some of the other species shared with our ancestors?

originally posted by: taylor73
a reply to: strongfp

Could you be more specific on some of the similarities that some of the other species shared with our ancestors?

Taxonomy is a very specific field of science dedicated to the form of a species, for example. We as humans have 5 fingers on each hand, two arms, two legs, five toes on each foot, a protruding nose, large brain, ears that stick out, the list goes on. We share these similarities with modern ape populations, this is fortified with a deeper science of biology and DNA comparisons.
If you got back to, say, Lucy we share the same taxonomic make up as lucy, which suggests we are a an almost direct descendant from her, and not maybe a horse or an alligator. if you can trace our DNA all the way back to lucy we most likely would see very similar DNA.

If you're studying this topic in detail I'm surprised how little attention you've paid to cooked food. Studies from the at least 2007, and maybe earlier, have proven that cooked food provides far more calories than raw food. As more calories are required by the brain than any other organ, this gave it more fuel to grow and develop advanced intelligence that we recognise today, coupled with a development in the digestive tract that could extract more nutrients than previously. This, above anything else, is the reason for our brain development and the advancement of our species.

Neanderthals also cooked and were not as stupid as they are commonly portrayed. Interbreeding was quite common in congested habitats.

O ok i get what your saying. So basically your saying its nearly impossible to know the true history of our evolution because their is thousands of other species throughout history that have characteristics that we have. So we don't know exactly which ones we evolved from, and it would be impossible to trace our DNA back. So what we do know of hour evolution is just a guess.

a reply to: 321Go

Yes you are right. The ability to cook food helped the evolvement of our brain, i mentioned in my paragraph briefly when i said "Some major changes that were happening around this time with the evolution of our species was that we learned to control fire by homo egaster about 1.5 million years ago, giving us access to better proteins from cooked foods."

originally posted by: taylor73
O ok i get what your saying. So basically your saying its nearly impossible to know the true history of our evolution because their is thousands of other species throughout history that have characteristics that we have. So we don't know exactly which ones we evolved from, and it would be impossible to trace our DNA back. So what we do know of hour evolution is just a guess.

Not exactly a guess, but more of a projection on what we have and what we know of biology, the fossil record, and taxonomy charts. In theory you can literally see a 'change' over time if you had a dead human specimen for every 10 years or so back to 'split' out of Africa, see us getting taller, brains getting larger, eyes becoming more binocular, etc.

It's just that fossils are rather rare to come by, and although we have millions of fossils there are only so many people to study them and paint the larger picture. But if you think about it, we have other fossils that suggest other ape populations have the same sort of linage, such as gibbons or gorillas, and we can come to a conclusion that we have a same evolutionary path, the same can be said for ALL living species on this planet.
Evolution never stops, and it'll continue to change every time a species procreates, or creates clones of themselves like a mantis does, all it takes is some sort of tiny mutation to happen.

originally posted by: taylor73
a reply to: 321Go

Yes you are right. The ability to cook food helped the evolvement of our brain, i mentioned in my paragraph briefly when i said "Some major changes that were happening around this time with the evolution of our species was that we learned to control fire by homo egaster about 1.5 million years ago, giving us access to better proteins from cooked foods."

Yes, I read that, but to me it sounds as if you're saying it was just as important as tool use or community living or anything else. What I'm saying is that, according to the studies made, cooked food marked a profound difference in how we developed as a species. After all, we are the only species to do it our development is somewhat different to most others.

a reply to: 321Go

After all, we are the only species to do it our development is somewhat different to most others.

We are also the only species to have developed language (not to mention the necessary "hardware"). Is that less important than the mastery of fire?

Yes i agree, it is more of a projection than a guess, but i would say a very good projection at least. I'm just not getting how we can come to the conclusion that we have the same evolutionary path as gorillas or gibbons. Yeah i guess gorillas and gibbons could develop the same evolutionary path as us, but it would take homo sapiens not being around and some climate change and a couple millions years and a lot of other factors for gorillas and gibbons to evolve like we are now.

a reply to: taylor73

but it would take homo sapiens not being around and some climate change and a couple millions years and a lot of other factors for gorillas and gibbons to evolve like we are now.

As well as the same mutations. Not necessarily millions of years but there is no reason that modern apes (other than the human type) could not develop "human" intelligence (except that they wouldn't be human). Unless, of course, they started competing with us.

Seems I saw a movie like that...

a reply to: Phage

haha yeah i agree good movie. Yeah if it happened before with us evolving from the ancestors of African apes to homo sapiens. Why couldn't something like that happen again?

originally posted by: Phage
a reply to: 321Go

After all, we are the only species to do it our development is somewhat different to most others.

We are also the only species to have developed language (not to mention the necessary "hardware"). Is that less important than the mastery of fire?

Of language use, that's not necessarily true, unless you are talking of large vocabulary language. Most mammals, for instance, use language albeit of limited vocabulary.

The best guess is that we expanded our limited vocabulary gradually, but it expanded to a much greater extent after we benefitted from a larger brain through greater calorie intake from cooked food.