Do the choices we make in life affect how humans evolve?

[AchillesWrathfulLove]

Does the individual matter in evolution? I remember watching a documentary about human evolution but I forgot most of it, it said that our ancestor decided to stand up and walk one day to see predators better (something like that) and that is the origin of how we came to walk upright. So one choice from an individual can affect population for evolution?

 

[Choppy]

That's not how evolution works.

The general idea is that all individuals within a given species have physical traits that are subject to a natural degree of random variation. Those traits are linked to the individuals' genetics. All of those individuals are also subject to a struggle for survival, the specific conditions of which are dictated by the local environment, predators, disease, etc. Within that variation of traits, some variations make it easier for some individuals to survive than others. Those with variations that make survival more likely tend to pass on those variations to their offspring more frequently than those with variations that make survival/reproduction less likely. Hence nature "selects" in favour of the individuals more "fit" for the specific conditions under which they need to survive.

You can think of it as a statistical phenomenon. It's possible that some individuals with physical traits that are rather unfavourable for survival will still survive. It's also important to remember that you're dealing with a full package deal too. Just because one trait makes survival a little less favourable doesn't necessarily mean that it's going to be efficiently eliminated from the gene pool.

So individual decisions don't drive evolution.

To go back to your example, humans didn't evolve to be bipedal because one homo erectus decided to stand up. As early human species spread out from forests to grassy plains there were survival advantages conveyed to those individuals who would spend more time on their hind legs. Traits like stubbier toes meant one could bear his or her full weight more comfortably, longer legs made taking bipedal strides more energetically efficient, and with two arms free, individuals can use those limbs for things like carrying food, babies and using tools, which also conveyed strong survival advantages. Individuals with higher concentrations of nerves and smaller muscles in their hands could then use those tools for more intricate tasks. At least, that's how I understand it.

You might want to check out this thread for more info:
Evolution Introduction

 

[Rive]

Usually, just as like one flip of the coin will affect a billion-flip statistics.

Of course, every useful gene started with a mutation, and at that point its elimination is a singular event with definitive effect. But any gene to show its worth needs to multiply first and become statistics: without that it is just noise.