favorite evolutionary development?

[mellowtigger]

Embryonic humans have features like gills and tail, and humans at birth have the trachea of chimpanzees. Embryonic great whales have teeth, but great whales at birth have baleen (keratin plates) instead.

The field of Evolutionary Development takes advantage of the observation that a developing embryo undergoes a mini-movie (but fast-forwarded) history of the evolutionary development of that particular species. The animal's oldest history appears in the youngest embryo and then progresses from there. In the case of humans, such developmental change occurs even past birth. So significant are the developmental milestones that appear in an embryo that Darwin himself advocated using these features to help identify on what branch in the Tree Of Life (YouTube video) an animal is placed.

We can see why characters derived from the embryo should be of equal importance with those derived from the adult, for a natural classification of course includes all ages.
- http://darwin-online.org.uk/content/frameset?viewtype=side&itemID=F373&pageseq=436

This relationship is not reliable enough to be regarded as a law of biology.  Recapitulation theory is discredited.  Still, these curious observations persist.

I think my favorite biological anachronism is the "chimpanzee throat" that humans are born with, because it shows that we are not fully human creatures even after that significant milestone of birth.  It entices me to think that perhaps we have failed to notice even more subtle changes that distinguish us from our primate relatives and our pre-human ancestors when they occur even after our trachea migrates into its "proper" modern human location.

What is your favorite evolutionary development?

Comments

[dangerdhotrod.livejournal.com]

>What is your favorite evolutionary development?

the ajna chakra (third eye!)

[mellowtigger]

I intend to do a followup to my "blue light special" post eventually, but here's a recent article about the possibility of machines that can see and interpret auras for us (in the scientific not the metaphysical sense).

http://www.livescience.com/health/090722-body-glow.html

:o)

[otterlover01.livejournal.com]

Loved the posting, love your great capacity for synthesis. This semester I will teach General Biology again. On thing I love to see are the faces of my students when I begin enumerating vestigial traits in organisms in general and then when I begin to talk about ours! Great you posted that link too! Big hugs dear Terry, Luis.

Re: :o)

[mellowtigger]

Yes, and we can see the influence of evolutionary forces on humans even within the course of our recorded history. Vestigial? Perhaps not yet.
http://www.physorg.com/news170010855.html

Also interesting is a new proposal for the start of the Tree.
http://www.physorg.com/news171263002.html

Re: :o)

[mellowtigger]

And here's an interesting collection of examples.
http://www.talkorigins.org/faqs/comdesc/section2.html

[foeclan.livejournal.com]

The hox genes, through which our study of evolutionary development in multicellular organisms is made possible.

Once you're done with End of Faith, you may want to borrow Endless Forms Most Beautiful, which is a very nice overview of evo-devo.

[mellowtigger]

Nice title. Yes, I'll be interested after I finish your other loaner.

[dodecadragon.livejournal.com]

I like the whole cell-division part and the eyes.

[jpeace.livejournal.com]

I love the ass. I don't think any other species gets one as good as ours.

[mellowtigger]

Human breasts are nearly indistinguishable from ass cheeks, given the same framing. Mother Nature trying to make women look appealing from either direction? *ignorant shrug* But which shape came first in humans: the cheek or the breast? Which is imitating the other?


Either way, it's probably a good thing that human asses don't look like this any more.

(Hrmmm. Did you know that the goatse.cx domain is for sale? http://en.wikipedia.org/wiki/Goatse.cx)