Later On

A blog written for those whose interests more or less match mine.

Archive for the ‘Evolution’ Category

The Evolutionary Advantages of Infidelity

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Interesting article by Amy Amos in Pacific Standard:

I hadn’t thought much about bird sex in a long time—30 years. But as I stood on a dirt road in the Canaan Valley National Wildlife Refuge in West Virginia this past summer, instinct (or perhaps muscle memory) took over. I lifted my binoculars to my eyes, listened for a distinctive bubbly song, and scanned the fence posts in the adjacent field. Sure enough, two male bobolinks were perched a few posts apart singing like mad to keep the other away from his territory.

Typical male behavior, I thought.

Years ago, as a wildlife biology major at Cornell University, I spent an entire summer watching a field of bobolinks do their thing. Males fiercely guarded their territories and females chose mates based on some mysterious combination of alluring song and impressive real estate. The mated pairs built nests and raised their broods together in seemingly monogamous bliss. On the surface, it was a Father Knows Best kind of scenario straight out of the Eisenhower era. But all of us on the research team watching knew that some of those daddies were fooling around on the side. We called the mistresses “secondary” and “tertiary” females. They raised their young on father’s territory, but he never acknowledged their existence. Instead, he doted faithfully on his “primary” female and helped her feed the brood.

As I watched a few bobolinks posture again this past summer for the first time since then, I suddenly saw things a bit differently. The fence posts morphed into bar stools and the bobolinks became men in some rowdy roadhouse. And I wondered: How did our research on bobolink sex influence thinking about human sex? This wasn’t a random question. Thirty years earlier, our team discovered something just beginning to be recognized: The mommy birds were fooling around on the side too.

Ever since Charles Darwin put his ideas about sexual selection down on paper in 1871 (in The Descent of Man and Selection in Relation to Sex) biologists had been reinforcing conventional thinking about female sexuality. Namely, that males of most species compete for as many females as they can get, that their “investment” in mating is low (sperm and copulation are energetically cheap compared with eggs and pregnancy), and therefore it’s to their advantage to seek out as many sexual partners as possible. Females, the thinking went, would gain no such advantage from having more than one sexual partner. Instead, it made evolutionary sense for females to choose one really good mate and put her eggs in one basket (figuratively and literally).

Scientists quibbled over the details and tweaked these ideas over the decades, but didn’t challenge them much. A.J. Bateman seemed to prove this point in 1948 with his classic study of fruit flies: Male fruit flies that mated with many females had more offspring that those who mated with few. But he found no such advantage for female fruit flies. Robert Trivers added consideration of parental investment to the discussion in 1972, noting that the sex that invests more in raising offspring would be choosy about mates, and the sex that invests less would compete with others of their gender for partners. But since females of most species—including humans—typically invest more time and energy in their offspring than males, scientific thinking didn’t change all that much.

Until DNA analysis.

By the mid-1980s, . . .

Continue reading.

Written by LeisureGuy

5 November 2014 at 11:10 am

Posted in Evolution, Science

How feathers evolved

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A nice little animation:

Written by LeisureGuy

11 October 2014 at 11:00 am

Posted in Evolution, Science, Video

Evolution of genes (in leaves) and memes (in violins)

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Very interesting article that rather clearly lays out an example of the evolution of a meme and compares that to the evolution of leaves.

“Meme” is a useful concept because we have always seen how our culture and cultural artifacts have changed over time—evolved—we had now word for the general phenomenon of cultural evolution. We could talk about the evolution of the violin or of neckties or of writing pens, but no name to lump all those instances under. Now we can talk about each as being memes—replicatable ideas—that evolve over time.

Written by LeisureGuy

10 October 2014 at 9:14 am

Posted in Evolution, Science

False views: That the Middle Ages were a time of engineering stagnation

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In fact, quite a few important technological developments and advances took place in the Middle Ages. I thought of that in connection with the cerebellum’s evolution, which, like the technology advance of the Middle Ages, still is often overlooked.

Written by LeisureGuy

3 October 2014 at 4:46 pm

Posted in Evolution, Science

Geneticists Decode the DNA Behind One of Earth’s Most Invincible Organisms

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Evolution can produce some amazing outliers on various attributes—-and this guy has several.

Written by LeisureGuy

13 September 2014 at 3:09 pm

Biology and math: Two fascinating articles

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Written by LeisureGuy

9 September 2014 at 2:56 pm

Posted in Evolution, Math, Science

Is this how it happened when animals first moved onto land?

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Written by LeisureGuy

27 August 2014 at 1:45 pm

Posted in Evolution, Science

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