Big Headed Babies, Barbless Penises

Caution: Adult Content. We will be discussing the Male Penis. It is intended for Adults only. If this type of conversation offends you, do not read this Week's Health and Science Segment. Thank You.

Hey folks,

This week's Health and Science Segment is very enlightening. I feel enlightened and very much grateful I now understand why I have both, a "big headed Baby" and a Barbless Penis. I just had to share with each and every one of you.

According to Reuters - How humans got big brains, barbless penises By Julie Steenhuysen – Wed Mar 9, 2:30 pm ET

CHICAGO (Reuters) – Missing chunks of DNA responsible for turning genes on and off help explain some key differences between chimpanzees and humans -- including why humans have big brains and why the human penis is not covered with prickly spines, U.S. researchers said on Wednesday.

The study, published in the journal Nature, reinforces the notion that genes that control the activity of other genes play a big role in what makes humans so different from other mammals.

To study this, David Kingsley of the Howard Hughes Medical Institute and Stanford University School of Medicine in California and colleagues compared the genetic code of humans to chimpanzees -- man's closest relative -- and other mammals.

They found 510 gene segments that are present in chimps and other mammals, but are missing in humans.

Nearly all of these were regulatory genes -- genetic switches that turn up or down the volume of nearby genes.

Then the team did a computer analysis to identify deleted DNA segments that were clustered around particular genes.

"We saw more changes than you would expect near genes involved in steroid hormone signalling," Kingsley said in a statement.

A number of deletions also appeared near genes involved in brain development.

The team kept narrowing the pool until they found a few dozen genes that they thought were involved in the evolution of particular human traits.

They found one of sections of DNA deleted in the human genome was responsible for producing sensory whiskers, such as those in mice, and prickly spines, like those found on the penises of many mammals.

"People are always surprised to hear that the penis of many organisms are covered with these spines," Kingsley said in a telephone interview.

I was. Not that I ever really thought of it. I was surprised to hear they do.

He said penile spines, or barbs, are typically present in species that mate quickly, such as male chimpanzees who must compete to fertilise one or two receptive females.

These spines -- made from keratin, the protein found in fingernails -- often lie over sensory receptors, and some experiments suggest removing them makes copulation last longer.

For humans, losing these penile spines might have prolonged intercourse and helped make monogamous relationships a more attractive option, the team said.

So sex is better without. Good to know.

Even more interesting to Kingsley, however, is that another of the DNA deletions was located near a gene that kept brain cell growth in check. The deletion of this DNA may have contributed to the development of larger brains in humans, he said.

Both of these traits may be related to meeting the reproductive needs of humans, which give birth to babies with large brains, requiring parents to mate in pairs -- at least long enough to care for their big-headed offspring.

So there you have it folks. Lacking certain DNA, means better sex, and Big Headed Babies. Now the story goes on to say that they hope in the long run, this new discovery will help us to better understand other, more important Physiological differences, including why Humans get diseases such as Arthritis, Cancer, Malaria, HIV, Alzheimer's and Parkinson's, and in this understanding, may lead to better treatment and a cure. But hey, I feel enlightened already. Don't you?
Peter

Sources:
Reuters - How humans got big brains, barbless penises