Evolution

Heather E. Heying has written a great thread on evolution and shared traits:

We were never orangutans. But we were—and still are—apes. As are orangutans. […] We are also fish. This does not mean that we are clownfish or eels or trout, or that we ever have been any of those things. […] We are also reptiles. This does not mean that we are Komodo dragons or skinks or T. rexes, or that we ever have been any of those things.

Traits that are new and shared at the level of a clade (“synapomorphies”—e.g. vertebrae in vertebrates, mammary glands in mammals) are different from traits found in just a few members of a clade (e.g. sequential hermaphroditism in clownfish).
[…]
Similarly, the *lineage* to which we belong is one long, uninterrupted string of sexual reproduction for at least the last 500 million years. Since we were indeed early fish, we have no evidence of anyone *in our particular lineage* going asexual.

The fact that, off on a couple different branches of the vertebrate tree *on which we never traveled,* there is some hermaphroditism, or parthenogenesis, does not mean that we have ever been a hermaphroditic, or parthenogenetic, species.
[…]
To summarize: the human lineage has been sexually reproducing for at least 500 million years.

Males produce tiny zippy gametes (sperm). Females produce large, sessile gametes (eggs). And it’s been that way for a very long time.
Heather E. Heying

We share the same ancestor as all other life on Earth but that doesn’t make us trees.

 

 

 

 

 

 

 

 

 

 

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