The monkey evolution "problem"

All too often I hear the same question on Twitter or somewhere on the internet : If we evolved from monkeys, why are there still monkeys?

There are several different ways to answer this question. I aim to show that the questions itself is pretty ridiculous. One of the most complete overall answers is here:
http://rationalwiki.org/wiki/How_come_there_are_still_monkeys



You can ask a very similar question using different analogies, and make the answer all too obvious. But the principle is still the same.

I don't actually think it's too useful to argue that we didn't evolve from monkeys. Although this may be strictly true (we evolved from a common ancestor of monkeys and humans that was different than monkeys are now) if the common ancestor was still around today as it was then, we would still call it a monkey. So better to say "not all monkeys evolved into humans, only some of them did". But we still need to re-iterate that those monkeys have evolved in different directions. One important point to make is that evolved adaptations need not appear outwardly as changes to physiology. For example, a monkey's eyesight could improve over 100s of thousands of years and we would not know without testing for it.

Good answering points: "Individuals do not transform, populations evolve!"

The "descent of man" is misleading as it implies an individual evolves dramatically throughout its own life! http://rationalwiki.org/wiki/File:Darwin-chart.PNG


"Don't fall for the old "Great Chain of being" fallacy. It's pre-scientific!"

"Evolution hasn't finished - it is always ongoing, but Selection Pressure determines the rate at which particular traits or mutations are favoured over others"

Let's explore some of the important issues here. "Speciation" is an important part of any complete answer to the monkey question. As a population grows, it expands its borders and moves out in different directions all around. Sometimes, it just so happens that a part of the expanding population can become isolated and no longer be able to mingle with the others. This can happen due to various environmental factors such as continental drift. For example, an island population of monkeys could drift slowly further out to sea and at some point be unable to complete the journey back to the mainland as it is too far to swim. At this point, the exact environmental conditions on the island on which they found themselves trapped would put pressure on their chances to survive and procreate. This is called Selection Pressure and is another key aspect of evolution. Until the monkeys have evolved to become highly adept at surviving in their current climes, they will be under selection pressure or "survival of the fittest". Once sufficiently evolved, the monkeys have found a niche and there is no particular advantage from one small mutation to the next, meaning that selection pressure is lessened. But by this time they may look decidedly different to their long lost cousins from the mainland and may not even be able to breed with them! If this was the case, we now have two different species!

Other important points: Species don't need to appear to change to succeed. Crocodiles have exhibited relatively slow physiological evolution (although their genome has obviously still evolved) and so ostensibly changed remarkably little in many millions of years. This is because they are settled firmly in an evolutionary niche in which they are the master predator!

Similar question, with obvious answer:

"If dogs are domesticated wolves, how come there are still wolves?"


Car Evolution: Maybe a useful tool?


"If the Ford Focus mark III evolved from the Ford Focus mark II, how come there are still Ford Focus mark IIs? "
This is quite a clever example (if you ignore the designed by man, transforming individual, and evolutionary "jumps" rather than a continuum, aspects) because not only does it expose the original question's stupidity, it also raises the further question: Why do Ford Focus mark Is also still exist? We can imagine that direct evolution from one state to another is represented in this analogy by an owner "trading in" their old model for a newer one at a Ford dealership, an act that is common enough to give the analogy at least some credence.

Again, we can see that earlier versions of the same car model fit a particular need for people and so have occupied a niche, removing much selection pressure. Ford Focus mark Is are still good and perfectly acceptable cars in their own way. Not all drivers trade in their motors for the newest models. For any particular purpose, mark Is can still suit someone's needs. This was the case when mark IIs came out, and still when mark IIIs came out. Applying this analogy to monkey evolution can be quite useful as it helps provide this further insight.

"We are still evolving from those monkeys that diverged and speciated from the main monkey populations, who are themselves still evolving, albeit in ostensibly subtler ways".