Originally posted by Heronumber0
I cannot see how humans can evolve from chimps.
If humans are just chimps with more mutations in their DNA then where the heck is the survival advantage? If you tell me that greater height is a
survival advantage for seeing further for food -I don't buy it! This is not a life or death situation.
If you tell me that humans accumulated gradual DNA mutations and then get selected by environmental/climatic factors, I don't buy that either.
How come most DNA mutations are harmful and even life threatening to humans, e.g. Thalassaemia, Motor Neurone Disease, Huntington's Disorder. The
only incidence of a mutation that is advantageous seems to be sickle cell anaemia which still debilitates sufferers.
Heck if we consider that brain size or intelligence gave us a survival advantage then think of people like Einstein and others who are INCAPABLE of
interacting with other human beings to give themselves a survival advantage.
Finally, if human adaptation gave us a selective advantage, why are there still chimps about nowadays?
You are 100% correct, human beings didn't evolve from chimps. Actually Humans and chimps both evolved from apes. Being as they are out closest
relatives then we must have a commmon concestor. All species are in a state of evoloutionary flux, certain environments force evoloution to occur
sooner than other places. And this ancestor would almost certainly appear to be more chimp than human if it were alive today.
Our concestor at best estimate lived 5-7 million years ago. At which point evoloutionary processes caused one population to evolve with more
humanlike qualities and one line with more chimplike qualities. DNA tells us that the human and chimp lines split, then interbred then diverged one
last time less than 5 million years ago. The X chromosome has a recent connection to the chimp genome. The hybrid males were infertile but the
females were not. You can pull some of that up from the Broad Institute of technology.
But regardless of the human-chimpanzee hybrids, eventually the two lines did split for good. And gradually, our ancestors changed from being something
that was willing to mate with a chimpanzee, into something that would rather hunt them for food, train them for entertainment, or sequence their DNA.
What was the first step? The first step, as it seems, is literally a step. A bipedal step, to be precise- the first thing to distinguish our ancestors
from chimpanzee ancestors is the ability to walk upright. But being able to walk upright doesn’t earn the scientific, phylogenetic designation of
human- we designate all human species by the genus “Homo” as in our binomial, “Homo sapiens.” But these first human ancestors weren’t human
enough to be considered part of our genus, and instead are called, “Australopithecus.” One species of this genus in particular is thought to have
been ancestral to humans- Australopithecus afarensis, one specimen of which has been nicknamed, “Lucy.” Like most of the Australopithecines, Lucy
lived in Africa.
Lucy, and the rest of her species, resembled chimpanzees in a lot of ways, but one difference is obvious- she walked upright, like a human. And not
just sometimes, the bone structure of her pelvis indicates that she was upright most of the time.
The next big change in human evolution was the expansion of the brain. This was different than a lot of scientists had expected- they had assumed that
a larger brain would have been the first change in the human-chimpanzee divergence, followed by other human traits such as bipedalism and tool use.
This turned out not to be the case- walking upright evolved first. But the expanding brain followed soon after, and in fact it’s how we classify
human species- that is, species that belong to the genus “Homo.” The first human, or at least the first recognizable human species to which
we’re willing to give the designation, is the Handyman, Homo habilis. The Handyman lived between 1.5 and 2.5 million years ago, and he gets his name
because rudimentary tools have been found with fossils of this species. These tools weren’t anything spectacular- just flakes of stone used as
rudimentary knives, for the cutting of meat off dead animals. It’s unlikely that the Handyman was a hunter- more likely, he would have taken meat
from already dead animals like a scavenger.
After Homo habilis, we find the next major step in human evolution. Homo erectus, or the Upright Man arose in Africa about 1.5 to 1.8 million years
ago. Homo erectus had a larger brain than Homo habilis, and its anatomy was more similar to modern humans. But the most interesting thing about Homo
erectus was its incredible success- it was the first human species to engage in actual hunting, and this had the effect of expanding its territory.
Because its diet became more reliant on animals than plants, Homo erectus began to migrate- and thus spread out of Africa, and colonized southeast
Asia, even going up farther north into Eurasia. There is also evidence that Homo erectus was able to control fire. There is some controversy about
whether Homo erectus evolved into a separate species once it migrated out of Africa and into Asia, but even if this happened, the two species are so
similar to make it almost impossible to tell today.
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