Monthly Archives: July 2010

Not quite a missing link

pink handfish

The image above is that of a pink handfish that according to BoingBoing “have fins that look an awful lot like hands. Instead of swimming, they walk on these fins.” National Geographic just published their pick of 10 weirdest animals of 2010 which includes the pink handfish. My favorite among the ten is the squid worm (pictured below)

Nat Geo Squid worm

Click on the image to see an amazing video of swimming squid worm

p.s. the title was inspired by the boingboing post itself.

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Sperm: The Evidence for Evolution?

“This is the first clear evidence that suggests our ability to produce sperm is very ancient, probably originating at the dawn of animal evolution 600 million years ago,” said Eugene Xu, assistant professor of obstetrics and gynecology at Feinberg. “This finding suggests that all animal sperm production likely comes from a common prototype.”

This week’s journal Nature Research Highlight section features an article originally published in PNAS that demonstrates that some species of promiscuous hermaphroditic flatworms have “a variety of sperm shapes”. The ejaculate containing sperms are sucked by these worms after sex and only those sperms that have “pair of long bristles emerging at the mid-point and a tail resembling a paint brush” can anchor themselves in “the female orifice after copulation, preventing the sperm from being sucked out.” This is one example of adaptive evolution in these worms to select for those sperms that can quickly implant themselves in the female reproductive system such that they have higher chances to produce a zygote.
Figure obtained from Nature

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Inbreeding may increase risk of certain cancers.

A study by I. Rudan of School of Public Health at University of Zagreb, Croatia claims that there is a higher incidence of cancer in both males and females in inbred island population. The article was not available for downloading thus, no additional details are available at this time. However, the cancers that seems to have increased in island populations are the recessive ones that is the cancers that are caused due to recessive mutations in anti cancer genes. If an individual is homozygous for these genes (both copies mutated) then they will have the cancer.

Whether or not this particular study in humans establishes a clear link between inbreeding and cancer (I say this because I cannot read this paper), ample reports have shown that low genetic diversity caused by inbreeding will make populations susceptible to new cancers. For example, a recent report in
Science and in other newspapers (click the image) show that facial cancer is pushing Tasmanian Devils to extinction. Inbreeding reduces genetic diversity and makes one susceptible not only to cancer but also to any other infectious agents.


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Back to Africa then Out of Africa?

I admit that I was actually unaware of the ‘Back to Africa’ theory until recently. The current belief is that primates evolved in Africa and migrated out of Africa. The “Out of Africa” migration occurred twice in case of Humans. First, Homo erectus left Africa. Recently, a hundred thousand years ago which is hundreds of thousands of years after Homo erectus, Homo sapiens began migrating Africa and reached distant parts of the world. This latter migration is called “Out of Africa 2”.

Apparantly there is a problem with this. “However, there’s a gap in Africa’s great ape fossil record between 14 and 7 million years ago. The Eurasian fossil record is rich at that time” according to Rutger University’s Anthropologist Rob Scott. He proposes when Europe cooled, some primates moved south in search of food and warmer climate. They encountered both in Africa. “Among the candidates for an ancestor of humans and other modern great apes are Rudapithecus hungaricus, Anoiapithecus brevirostris and Ouranopithecus macedoniensis. These apes have human like features and Ouranopithecus lived in Greece, was well-suited to eating nuts and tubers, and possibly was the first bipedal.

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