Evolution (uh-oh)

After watching many videos of Richard Dawkins using laymen’s terms to describe the evolutionary process, I decided it was time to turn to a more… informative side of the inter-webs.

Most of those videos end with the famous statement, “We did not evolve from monkeys, but rather a common ancestor.”

With this in mind, can anyone explain what that common ancestor is believed to be? And how did this ancestor end up splitting into two separate species?

The last common ancestor of humans and other apes is unknown; however Pierolapithecus catalaunicus is a possibility.

As to the second question, that’s how mutations work. Some mutations are successful, and some aren’t. If the mutations are successful and the non-mutated species is successful, you have divergence.

I think it may be misleading to claim that we did not evolve from a monkey, because we most likely did evolve from a primate. We didn’t evolve from any current primate (yes, not all primates are monkeys.)

Here is a wikipedia article on the subject


The most recent common ancestor between humans and chimpanzees is believed to have lived about 5-7 million years ago. This is based on fossil evidence (morphological similarities) and molecular (DNA) evidence. We don’t know exactly what species was the last common ancestor, but it was likely similar to some mentioned in the link above, such as Ardipithecus or Sahelanthropus.

How did this species end up splitting into two? It split into many more than two (there are many species that went extinct that descended from this ancestor), but the only two lines (three, really, considering that Chimps and bonobos are separate species) still around today are humans and chimps/bonobos. But it split for the same reasons for any speciation- one of the simplest to understand is geographical separation: two groups become separated by something like a river or an earthquake and evolve to adapt in separate environments.

Well, to be fair, the common ancestor of humans and monkeys would itself be best described as a monkey. What people mean when they say “we did not evolve from monkeys” is that we didn’t evolve from any currently-extant species of monkey.

Oreopithecus bambolii is the suspected last common ancestor between the gibbons (lesser apes of family Hylobatidae) and the great apes of family Hominidae, from which the modern Homo sapiens is derived.

As for “how did this ancestor end up splitting into two separate species?” I’ll refer you to Ernst Mayr’s What Evolution Is and Stephen J. Gould’s The Structure of Evolutionary Theory for two very comprehensive views on the mechanics of evolutionary processes and the theory of natural selection. We of course have not directly observed the evolution of primates and can only infer the paths and selective pressures from the sparse fossil record, but from that data combined with knowledge of zoology, microbiology, genetics, and anatomy we have developed a rich and internally consistent history of primate and human evolution, the body of which rivals the sheer amount of data and human effort in any other area of science including astronomy and high energy physics. To try to survey all of this in any useful degree of detail in the span of a single post or even a long essay would be a hopeless task.


It’s worth saying because it forestalls the question “if we evolved from monkeys, why are there still monkeys?”

You would think so, anyway.

I found Dawkins books to be extremely informative and helpful to my understanding. Don’t rule his writings out. You might have to switch at some point from internet videos to books.

It also decreases the power anti-science religious nuts have over people who are on the fence re: evolution.

I learned a lot from Dawkins’ “The Selfish Gene”, and I loved “The Ancestor’s Tale”. Those are the only two of his I’ve read so far.

I’d recommend “The Greatest Show on Earth” for the present purposes. I thought it was outstanding, highly informative, and very accessible.

The common ancestor of humans and the other twenty or so species of apes (gorillas, chimpanzees, orangutans, and gibbons) was an ape. That is, it was a tailless, tree-dwelling primate.

The common ancestor of that ape and the eighty or so species of Old World monkeys would be classed as a monkey if we had a specimen today. I am not sure off the top of my head if the New World monkeys split off from the Old World before or after apes developed from Old World monkeys.

So, it is not a question of this “common ancestor” splitting off into two species. Our family tree looks more like a bush, with a lot of dead branches. You are going to start believing that humans are somehow “special” if you do not understand that it is not “humans” versus “everything else” but humans *and *everything else.

We’re not just dirty monkeys. We’re actually really awkward fish.

Or worse…

I loved “Climbing Mount Improbable.” It constructs a metaphor of an evolutionary process as climbing a mountain, and shows how, although one might think that arriving at some given summit or high ridge is unlikely, it’s really just the sum of a great number of much smaller ascents. It’s another way of rebutting the “irreducible complexity” argument, by showing that vast complexity can be the sum of large numbers of very small increments.

The eagle’s eye didn’t evolve all at once.

But…well, I’ve pretty much given away the book!

When you’ve answered, “If we evolved from monkeys, why are there still monkeys?”, then you have to answer, “If birds evolved from dinosaurs, why are there still…” When do we get tired of arguing science with people that believe in magick? It’s pointless, because facts have no bearing on superstition.

Before. That means we apes are monkeys, too!

And, remarkably, after the two continents split.

Thank you, that was fascinating
A source of confusion in determining the exact age of the Pan–Homo split is evidence of a more complex speciation process rather than a clean split between the two lineages. Different chromosomes appear to have split at different times, possibly over as much as a 4 million year period, indicating a long and drawn out speciation process with large scale hybridization events between the two emerging lineages… Complex speciation and incomplete lineage sorting of genetic sequences seem to also have happened in the split between our lineage and that of the gorilla, indicating “messy” speciation is the rule rather than exception in large-bodied primates.
So, our ancestor were miscegenating pervs who did naughty things with other apes. So much for “racial purity”, we started out a mess.

I think the better answer to “If we evolved from monkeys, why are there still monkeys?” is “If I’m descended from my mom, why is my mom still alive?”. Or better yet, “If I’m descended from the <my last name>s, why are there still <my last name>s?”.

I always preferred the reply from a scientist, not sure who he was, that said:

“There are still monkeys because there is still work to be done around the trees.”

The monkeys were lucky, IIUC our ancestors likely got rid of other close relatives that lived outside the jungle and tree areas. Unfortunately, there is a good chance that the luck of the monkeys and other big apes is running out as man seems to be willing to finish the job and make the question moot.