system
Given the following post, respond as if you're commenting on Reddit:
human
Evolution Question: How did complex organisms (with many interdependent organs) evolve? Wouldn't all of the organs have to appear simultaneously?

Since none of an organism's organs would survive without each other, how did they come about? Similarly, how did the bee/flower relationship evolve?
gpt
As with most questions in evolution, the answer is basically: very slowly.

In a lot of cases the organs don't necessarily come to fruition at the same time, but they do grow in cohort together. And there are hundreds of stages in between which are interesting.

This is why you get all of the weird phenomena like your reproductive organs starting up with your kidneys in your torso and then later on before birth travelling down to their rightful place (Some dogs, other mammals as well but particularly dogs, have testicles stuck in their torso which need to be surgically removed because of this).

If you want to see anything human specific, a great way to see how things evolved is to watch an embryo develop. We're made in such a way that often the only way to completely create a human body is to follow the steps evolution took, just to put everything in the right place. That'll give you a good idea as to what evolved when and with which other organs.


Odd fact, in the last couple of months of pregnancy a foetus develops a full body coat of hair which it then sheds before birth, called the Lanugo (if the baby is premature enough it will be born with this coat). Most people have no idea why this happens but it is actually an artefact from when we were still monkeys. They were hairy all over obviously, and Chimps tend to develop this lanugo at a comparable stage of gestation, which they then keep.