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Having sex to become pregnant: Why it is necessary?

15 Aug

The gorgeous plumes of a peacock are a classic example of a trait that emerged solely for sex appeal.

“Some are fancy on the outside.  Some are fancy on the inside.  Everybody’s fancy.  Everybody’s fine.  Your body’s fancy, and so is mine.”  –Fred Rogers (♫ listen here)

“Some mollusks (not many) can have children merely by sitting around and thinking about it.”   — E.B. White, Is Sex Really Necessary?

As it turns out, snail sex (a snail is a type of mollusk) is really far out:  Some can self-fertilize, some stab their mates during foreplay with harpoon-like “love darts,” and most snails have two sex organs, so they can do it both ways at the same time.  As E. B. White observed, “mollusks are infinitely varied in their loves, their hates and their predilections.”  See snails doing it!


Weekly reading: Your Inner Fish

16 Mar

“Carl Sagan once famously said that looking at the stars is like looking back in time.  The stars’ light began the journey to our eyes eons ago, long before our world was formed.  I like to think that looking at humans is much like peering at the stars.  If you know how to look, our body becomes a time capsule that, when opened, tells of critical moments in the history of our planet and of a distant past in ancient oceans, streams and forests.  Changes in the ancient atmosphere are reflected in the molecules that allow our cells to cooperate to make bodies.  The environment of ancient streams shaped the basic anatomy of our limbs.  Our color vision and sense of smell has been molded by life in ancient forests and plains.  And the list goes on.  This history is our inheritance, one that affects our lives today and will do so in the future.”

The overarching story of Your Inner Fish is that of descent with modification.  We are modified descendents of our parents, as were they, as were their ancestors, back to the origin of life.

Neil Shubin, the paleontologist and anatomy professor who co-discovered a significant fossilized “intermediate” between fish and land-dweller, tells this story with humor and grace.  Anecdotes about particular scientists and their historic experiments infuse the whole book with a tone of enthusiastic discovery.

At first glance, parts of our bodies seem to make no sense at all.  Looking at the winding nerves in our heads, or at the circuitous route that sperm takes from scrotum to penis, our bizarre plumbing and circuitry calls to mind the wiring of an old building with new innovations added on or wound around defunct or outdated structures.  That’s exactly because the human body, 3.5 billion years in the making, was built in just that way. 

For example, Shubin tells, us, 3 percent of our entire genome is devoted to genes for detecting various odors, many of which are useless to us but may have been critical to our mammal ancestors’ survival.

Hiccups irk us, but this likely remnant from our amphibious past allows tadpoles to pump water without flooding their lungs.

Shubin tells stories about particular genes—including Sonic hedgehog that is crucial in the development of limbs, or Hox genes that control the organization of the body—which function similarly across various species, from humans to fruit flies, mice to sharks.  Various mad, Frankensteinish experiments have shown amazing results from the swapping of genes among them.

“The best road maps to human bodies lie in the bodies of other animals,” writes Shubin.  “…We are not separate from the rest of the living world; we are part of it down to our bones [and] even our genes.”

How am I different from my dog?

14 Jan

Fergus smiles

It is not our differences that divide us. It is our inability to recognize, accept, and celebrate those differences.” –Audre Lorde

My dog, Fergus, is furrier than I am. He detects smells more capably, and with a wetter nose. And, this one’s a biggie, words never come out of his mouth.

But while genes help explain the diversity of life on our planet, they show us to an astonishing degree that all we living things are similar.

Gene for gene, people are said to be more than 99 percent similar, one guy to the next. Related genes in humans and apes are almost as alike. We begin to see more differences when we compare the human genome to the genomes of other animals, like dogs and mice, but not much. The related genes of mice and men are roughly 85 percent the same. Good blog. Fetch!

Weekly Reading: It Ain’t Necessarily So

18 Nov

Richard Lewontin’s “It Ain’t Necessarily So: The Dream of the Human Genome and Other Illusions,” is an erudite collection of essays for readers interested in the recent politics and the intellectual history of genetic ideas. Continue reading

Weekly reading: The Ancestor’s Tale

27 Oct

WE– you and I– literally share a common ancestor with this unworldly creature!  And for that matter with all other life on planet Earth.

“The ravishingly beautiful Cestum veneris is one of those rare animals whose English and Latin names mean exactly the same thing, Venus’s girdle, and no wonder: the body is a long, shimmering, ethereally beautiful ribbon, too good for a goddess.” –Richard Dawkins  (Video from YouTube user quixoticknight used with permission.)

In The Ancestor’s Tale (Houghton Mifflin, 2004), Richard Dawkins guides the reader on a “pilgrimage” backward in time toward the common ancestor of all living things, which lived more than 3 billion years ago.

Tracing the evolutionary thread of humankind, the author describes 40 “rendezvous points” where humans come to share ancestors with distant cousins, from chimpanzees to eubacteria. Continue reading