bascule Posted October 21, 2009 Share Posted October 21, 2009 Is there a genetic link to the self-similarity exhibited by humans? I'm specifically referring to our limbs and our digits. Our hands have four fingers and a thumb. Our bodies have four limbs and a head. We have five toes on each foot, one very different from all the rest. Our hands and feet receive blood through our wrists and ankles. Our bodies once received blood through our umbilical cords. Is this sort of self-similarity a coincidence, or is there a genetic underpinning? Link to comment Share on other sites More sharing options...
Mr Skeptic Posted October 21, 2009 Share Posted October 21, 2009 No, it's probably not a coincidence. Self-similarity is quite a theme in nature. All the fractal patterns, tree branching, for example. We also have a lot of self-assembly, though some things need additional help to be assembled. Link to comment Share on other sites More sharing options...
toastywombel Posted October 21, 2009 Share Posted October 21, 2009 What would be interesting to find out is if the gene(s) that cause these similarities in humans are the same exact genes that cause the similarities in other animals. The more we study genetics, it seems to me, the more we realize how similar humans are to the other animals. I remember before we mapped the human genome many scientists predicted that humans may have up to 100,000 genes, because most of our animal counter-parts had only 20,000-25,000. After it was all said and done it turned out humans had about 20,000-25,000 genes. Lol sometimes man can be a little egotistical. Link to comment Share on other sites More sharing options...
Mokele Posted October 21, 2009 Share Posted October 21, 2009 That the hands/feet and the body have the same number of immediate branches is nothing more than coincidence. Consider how many organisms have less than 5 digits, or have lost one or both pairs of limbs. The genes and embryology behind them are different too. So basically, yes, it's a coincidence. Link to comment Share on other sites More sharing options...
bascule Posted October 22, 2009 Author Share Posted October 22, 2009 Was the common ancestor of all mammals 5-toed? Just curious... Link to comment Share on other sites More sharing options...
iNow Posted October 22, 2009 Share Posted October 22, 2009 Was the common ancestor of all mammals 5-toed? Just curious... Hopefully someone will correct me if I'm wrong, but some quick googling implies to me that the answer is yes. It looks like the first mammal was Hadrocodium Wui, which is this: ... and that little dude obviously has five fingers/toes. Link to comment Share on other sites More sharing options...
Mr Skeptic Posted October 22, 2009 Share Posted October 22, 2009 Hm, but it also has 6 limbs (paws, head, tail) rather than just 5. Link to comment Share on other sites More sharing options...
Mokele Posted October 22, 2009 Share Posted October 22, 2009 Five toes is the basal condition for all *extant* tetrapods, but certainly not all tetrapods including extinct spcies. Back when vertebrates first crawled onto land, they had a wide variety of toe numbers, in some cases more than a dozen on each foot. Eventually, a five-toed form gave rise to all extant vertebrates, probably simply due to it coincidentally having some other trait which actually mattered. The basal condition is pretty much "lizard" - a head, a tail, and 4 limbs with 5 toes each. From there, things have diverged, and we're actually very odd creatures in comparison to most other tetrapods. Link to comment Share on other sites More sharing options...
bascule Posted October 23, 2009 Author Share Posted October 23, 2009 Heh, never thought of a tail... Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now