Evolution

Two papers published this week have proposed explanations regarding the evolution of social monogamy among mammals and especially primates.  Of three competing hypothesis, one proposes that a driving force in establishing social monogamy was the protection of offspring by preventing male infanticide, while the other proposes that social monogamy is the result of female intolerance towards each other and a low population density that simply prevents males from adequately "guarding" females from other males (1).

A study of mortality and fertility patterns using seven species of wild primates (apes, monkeys etc.) compared with similar data from hunter-gatherer humans found that menopause sets humans apart from other primates.


Most mammals aren't monogamous, nor are most anything except birds, where it happens in about 90% of cases. 

It's actually quite rare in mammals (5%), so why did it evolve? Was it to be better parents together, to protect offspring from being killed by other males or instead to protect women from competitors? Well, it depends on who you ask.

Being a solitary individual who can't run all over the place protecting females from other males wins the prize, according to Cambridge zoologists Lukas and Clutton-Brock, who looked at 2,000 species of mammals and determined that when breeding females didn't like each other and female density was low, a monogamous mating strategy developed because males were unable to defend multiple females from other males.

Male guppies must not be very sexy, because they have evolved an extreme way to hold on to a female that interests them, even if that affection is unrequited: claws on their genitals to make it more difficult for unreceptive females to get away during mating.


Adineta vaga, the delloid rotifer, abandoned sex yet still produced more than 460 species over evolutionary time.

Rather than the standard way of using sexual reproduction to weed out harmful mutations to its DNA, this tiny aquatic animal appears to have adopted other strategies to maintain lineages over millennia that aren't burdened by genetic damage or killed off altogether.


When is a tuna more like a seahorse than a marlin?

Science!

The first comprehensive phylogeny of the "spiny-rayed fish," a group that includes about a third of all living vertebrate species, has been published in the Proceedings of the National Academy of Sciences.


An unknown physiologic mechanism of evolutionary biology has been the ability of mammals to manipulate the sex ratios of their offspring as part of a highly adaptive evolutionary strategy. A new paper analyzing 90 years of breeding records from the San Diego Zoo says that mammalian species can "choose" the sex of their offspring in order to beat the odds and produce extra grandchildren.


Madagascar represents only one percent of the earth's area but is home to about three percent of all animal and plant species on the planet - it has long been known as a hotspot of biodiversity.

New research in Proceedings of the Royal Society B suggests the island's heyday of species development may be all but over. 


Sir Archibald Henry Bodkin, KCB (1862–1957) was our British Director of Public Prosecutions from 1920 to 1930.  He particularly took a stand against the publication of what he saw as ‘obscene’ literature.