Mankind has not stopped evolving

Watch this.



Last sentence: "Chances are decades from now, we'll look pretty much the same."

"Decades from now"?!?! Are you absolutely kidding me? What a ridiculous thing to even consider. Decades from now nearly all species will look pretty much the same as they do now. When humans evolved big brains, did it happen in "decades"? That's like saying there is no galaxy evolution (= development), because decades from now all galaxies will look just the same as they do now.

It is true that some selection pressures have been removed, such as selection against bad eyesight, diabetes, low sperm count, and many other diseases. There is probably also not selection for being more intelligent - people of low IQ (for one measure) do not appear to have any less children than those of high IQ (is it in fact the other way around?). But this is now. Selection pressures are dictated by the environment, and we can only say anything about what selection will do as long as we know what the environment will be like. And does anyone really think nothing will happen in the future to our environment? No global climate change will affect us? No loss of species diversity, habitat loss, continental drift, changes in the Gulf Current, nearby gamma-ray bursts, meteors, supervolcanos, or other things that we don't know of?

The statement that there is no selection pressure anymore is also wrong. There is lots of purifying selection, meaning selection that makes sure that humans do not change. This selection pressure is in fact exactly why we do not evolve - for example selection against having larger brains, since babies with larger heads tend to die in child birth (if it were not for c-sections, my oldest son would likely not have been born, his mother dying with him). But note that this need only be true for some aspects of human morphology - while one trait is under purifying selection, another may be under positive selection, forcing a change in the long term.

Additionally, evolution does not equal natural selection. Random chance can change populations, too. Genetic drift is weak when the effective population is large, which is arguably is with humans right now, but that may quickly change when famine or disease or other catastrophic events suddenly kill off everyone in the northern hemisphere, for example. And then in one fell swoop the human population will have changed, and we call that evolution too.

One aspect of human morphology that interests me are feet. I don't think we are presently under selection for having five distinct toes. My guess is that a human born with just two toes would be totally fine. I know people with some toes fused, and it makes no difference in the lives. They can walk like the best of them, and since we wear shoes, no potential mate will react negatively to gross toes (okay, I'm putting things a little on edge here). Toe morphology drifts, and once humans lose the ability to make shoes, we may have changed significantly since we first started wearing them.

No, mankind has not stopped evolving. At all. Some selection pressures have changed, but they may change again when the environment changes. Evolution takes time, not "decades".

Also, Michio Kaku is a string theorist. Here's one for you: String theory is not a field of physics, but of mathematics. Please stop saying what the real world is like based on string theory, at least until you can actually verify your hypotheses experimentally.