In Praise of Promiscuity

IT has been a year since we discussed this happy topic. That’s when we posted: Female Promiscuity and Evolution. Now have some interesting information from the University of Exeter. Their news office reports this story Does promiscuity prevent extinction? Here are some excerpts, with bold added by us:

Promiscuous females may be the key to a species’ survival, according to new research by the Universities of Exeter and Liverpool.

Your Curmudgeon finds this to be exciting news. Let’s read on:

Published in Current Biology, the study could solve the mystery of why females of most species have multiple mates, despite this being more risky for the individual.

Here’s the abstract: Polyandry Prevents Extinction. You will need a subscription to read the full article. We continue with the news release:

Known as ‘polyandry’ among scientists, the phenomenon of females having multiple mates is shared across most animal species, from insects to mammals. This study suggests that polyandry reduces the risk of populations becoming extinct because of all-female broods being born.

How big a risk is that? Here’s more:

This can sometimes occur as a result of a sex-ratio distortion (SR) chromosome, which results in all of the Y chromosome ‘male’ sperm being killed before fertilisation. The all-female offspring will carry the SR chromosome, which will be passed on to their sons in turn resulting in more all-female broods. Eventually there will be no males and the population will die out.

Egad! Moving along:

For this study, the scientists worked with the fruitfly Drosophila pseudoobscura. They gave some populations the opportunity to mate naturally, meaning that the females had multiple partners. The others were restricted to having one mate each. They bred several generations of these populations, so they could see how each fared over time.

A splendid test. What happened? Here’s another excerpt:

Over fifteen generations, five of the twelve populations that had been monogamous became extinct as a result of males dying out. The SR chromosome was far less prevalent in the populations in which females had the opportunity to have multiple mates and none of these populations became extinct.

A great triumph for the promiscuous females! On with the news:

The study shows how having multiple mates can suppress the spread of the SR chromosome, making all-female broods a rarity. This is because males that carry the SR chromosome produce only half as many sperm as normal males. When a female mates with multiple males, their sperm will compete to fertilise her eggs. The few sperm produced by males carrying the SR chromosome are out-competed by the sperm from normal males, and the SR chromosome cannot spread.

And now we come to the end:

Lead author Professor Nina Wedell of the University of Exeter’s School of Biosciences, said: “We were surprised by how quickly – within nine generations – a population could die out as a result of females only mating with one partner. Polyandry is such a widespread phenomenon in nature but it remains something of an enigma for scientists. This study is the first to suggest that it could actually save a population from extinction.”

So, gentlemen, when the love of your life is unfaithful, try to look on the bright side. She’s averting extinction. Darwin would understand. Surely you can too.

Update: See Darwin, Evolution, and Promiscuous Squirrels.

Copyright © 2010. The Sensuous Curmudgeon. All rights reserved.

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9 responses to “In Praise of Promiscuity

  1. Olivia is delighted you now understand why she dumped you.

  2. retiredsciguy

    Hey Curmy,

    This is all well and good, but I’d be more interested if you had found some studies showing the benefits of male promiscuity. Start working on that, will ya?

  3. retiredsciguy

    By the way, if you’re interested in doing the original research yourself, you shouldn’t have any problem getting grant money from Congress, or perhaps from the Clinton Foundation, the Tiger Woods Foundation, the John Edwards Foundation, the Mark Sanford Foundation, or any number of other sources out there.

  4. Great Claw says: “Olivia is delighted you now understand why she dumped you.”

    If she wants to preserve the species, that’s fine. But where do you fit into the picture? The first thing she’d do is cross a specimen like you off her list.

  5. retiredsciguy says:

    This is all well and good, but I’d be more interested if you had found some studies showing the benefits of male promiscuity.

    Don’t need no nerdy studies. I’m just doing what comes naturally, so to speak.

  6. Historically, polyandry has been used by small nomadic groups who needed to keep populations small and under control, while polygyny was used when there was a large drain on male populations, such as ongoing wars.

  7. Dr. Strangelove had a better idea:

    General “Buck” Turgidson: Doctor, you mentioned the ratio of ten women to each man. Now, wouldn’t that necessitate the abandonment of the so-called monogamous sexual relationship, I mean, as far as men were concerned?

    Dr. Strangelove: Regrettably, yes. But it is, you know, a sacrifice required for the future of the human race. I hasten to add that since each man will be required to do prodigious… service along these lines, the women will have to be selected for their sexual characteristics which will have to be of a highly stimulating nature.

  8. Excellent commentary, Longie.

  9. Tomato Addict

    Genetic studies of some human populations suggest the non-paternity rate is somewhere in the 5-10% range. This suggests that humans won’t be dying out from this particular difficulty.