Why women should love spineless men

More than one woman over the years has called me spineless. At the time I was insulted but now it seems that being a spineless male has a distinct and most pleasant advantage.

The BBC reports that scientists believe men once had small spines on their genitalia along the lines of those found in chimpanzees, cats and mice.

A study published in Nature gave details of an analysis of the genomes of humans, chimpanzees and macaques which indicates that a DNA sequence thought to play a role in the production of these spines have been deleted in humans, but has been preserved in other primates.

The researchers at Stanford, Georgia and Pennsylvania State universities in the US wanted to trace evolutionary changes in human DNA.

They compared the human genome with those of the chimpanzee and macaque, and came up with 510 stretches of DNA that have been conserved in our primate relatives but deleted in humans. Nearly all them appear to play a regulatory role in the function of nearby genes.

Penile spines are barb-like structures found in many mammals. Their role remains under debate, and they may play different roles in different species.

They may increase stimulation for the male during mating. They might also play a part in inducing female ovulation in a small number of species, but there is evidence that they can cause damage to the female too. There is also the suggestion that they might have evolved to remove "mating plugs" - material that some male species deposit in the female genital tract to block other males' attempts to fertilise the same female.

The researchers believe the loss of these spines in humans may be related to changes in human courtship. The loss of spines, they say, would result in less sensitivity and longer copulation, and may be associated with stronger pair-bonding in humans and greater paternal care for human offspring.

Whether the theories about the function of penile spines are correct or not I am glad that they have been evolved away[ the not-wife of course is even happier!

Meanwhile in a Mexican cave…

For centuries a group of indigenous people asked their gods for bountiful rain by stunning the cave's fish with a natural plant toxin. Once the fish have succumbed, the Zoque people scoop them into baskets for eating. Live Science scientists have found that the practice has impacted on the fish's evolution.

Perhaps unsurprisingly those fish that are resistant to the anaesthesia survive to pass on their genes, while the others simply die

The religious ceremony is held in the Cueva del Azufre at the end of the dry season during the holy week before Easter. The Zoque grind up the toxic, carrot-shaped roots of the tropical barbasco plant and mix them with lime to form a paste, which they wrap in leaves. They place the bundles about 110 yards (100 meters) into the cave to poison its waters and anesthetize fish, which the Zoque believe are gifts from gods that inhabit the underworld. The collected fish supplement the meals of the Zoque until crops are ready for harvest.

Michael Tobler, an ecologist from Oklahoma State University Tobler and his colleagues were in the area investigating the Atlantic molly (Poecilia mexicana), to figure out how these fish made their way from the surface all the way underground. And once in the dark reaches of the cave, Tobler wondered how they survived in the cave system despite the presence of toxic hydrogen sulphde there.

They learned about the ceremony in 2007 and so to see whether it influenced the evolution of these fish, the researchers collected specimens from the annually poisoned waters as well as areas upstream that hadn't been affected by the ritual. They next placed barbasco root toxin into tanks holding the fish.

Fish exposed to the annual ritual indeed proved more resistant to the toxin than fish that lived elsewhere, able to swim in poisoned waters for roughly 50 percent longer. As such, the poison from the ceremony apparently has over time helped select fish that can tolerate it — fish that cannot get captured and killed by the Zoque.

Ironically the fish do not seem to be good eating: "We actually got to eat some of these cave fish," Tobler "They're not very good, by the way.”

Religion aiding evolution who’d a thunk it?

Evolution in action?

Last month National Geographic carried an interesting item which may well be an example of evolution in action Scientists are decoding how a species of Australian lizard is abandoning egg-laying in favour of live birth.

Along the warm coastal lowlands of New South Wales (map), the yellow-bellied three-toed skink lays eggs to reproduce. But individuals of the same species living in the state's higher, colder mountains are almost all giving birth to live young. Only two other modern reptiles use both types of reproduction.

Evolutionary records shows that nearly a hundred reptile lineages have independently made the transition from egg-laying to live birth in the past, and today about 20 percent of all living snakes and lizards give birth to live young only.

One of the mysteries of how reptiles switch from eggs to live babies is how the young get their nourishment before birth. In mammals a highly specialized placenta connects the foetus to the ovary wall, allowing the baby to take up oxygen and nutrients from the mother's blood and pass back waste.

In egg-laying species, the embryo gets nourishment from the yolk. The mother forms eggs, but then retains them inside her body until the very last stages of embryonic development. The shells of these eggs thin dramatically so that the embryos can breathe, until live babies are born covered with only thin membranes—all that remains of the shells.

Both birthing styles come with evolutionary tradeoffs: Eggs are more vulnerable to external threats, such as extreme weather and predators, but internal fetuses can be more taxing for the mother. For the skinks, moms in balmier climates may opt to conserve their own bodies' resources by depositing eggs on the ground for the final week or so of development. Moms in harsh mountain climates, by contrast, might find that it's more efficient to protect their young by keeping them longer inside their bodies.

Interesting stuff!

When bacterial infection is a form of protection

Last week the Guardian reported on a relationship evolving between a bacterium and a fruit fly in the US. The relationship is highly beneficial as it protects against a parasitic nematode.

Parasitic nematode worms Howardula aoronymphium infect female larvae of the fruit fly Drosophila neotestacea, where they prevent the eggs from developing. The worms also reduce mating success and survival in male flies.

"The mother worm gives birth to literally thousands of live young in the abdominal cavity of the fly," said John Jaenike of the University of Rochester in New York, who led the research. "From there they work their way into the ovaries. The female fly thinks she's laying eggs, but she's actually laying nematodes," he said.

But the flies have a trick up their sleeve. For years researchers have suspected that Spiroplasma, a bacterium that is passed directly from mother to larva through the egg, is protecting the flies.

They found that parasitised females became more fertile after exposure to Spiroplasma. The nematode-carrying flies that had not been infected with bacteria became sterile.

Spiroplasma seems to protect the flies from the ill effects of worm infection in a textbook example of symbiosis. Both the fly and the bacterium benefit from the situation: the fly gets protection from worms, and the bacterium gets somewhere to live.

The symbiotic relationship between fly and bacterium seems to have been spreading across the US over the past three decades. "The effect in the wild is absolutely whopping," said Jaenike. "Back in the 1980s every nematode-infected fly was completely sterile ... The situation is different today. They were getting clobbered in the 1980s but now they have quasi-normal nematode infection levels."

In the 1980s, only 10% of wild flies were infected with Spiroplasma in the eastern US. That figure had jumped to 80% when a survey was conducted in 2008. Wild females infected with the bacterium had more than 10 times as many eggs in their ovaries as uninfected females.

The bacterium appears to be spreading from east to west across the country, so Jaenike wants to repeat the survey this year to find out if Spiroplasma has reached the west coast.

"The speed of the spread is interesting, but what I personally find astounding is that we can see it," said Jaenike. "Something happening in 20 years is a split second on an evolutionary timescale."

He compared the way the bacterium is passed from generation to generation of flies to how mitochondria are passed from parent to child in humans. "What we are seeing are the early stages of a beneficial relationship. Who knows where it will lead?"

Well there you have it I could go into a rant about the heresy of evolution but it wouldn’t really be that convincing now!

More science news, this time early gorillas.

The apparent discovery of a new species of great ape that roamed Africa 10m years ago may force scientists to rethink the earliest steps of human evolution. Fossil hunters working along the Afar rift in central Ethiopia have discovered remnants of teeth they claim belonged to a previously unknown species of gorilla they named Chororapithecus abyssinicus.

If confirmed, the discovery could redraw the evolutionary tree of primates, suggesting that humans and chimpanzees split from their gorilla-like ancestors earlier than thought. Geneticists have previously put the date at which the human and chimpanzee lineage split from gorillas at around 7m years ago, with humans and chimps diverging 5m years ago.

A team led by Gen Suwa at Tokyo University Museum recovered one canine and eight partial molars from rocky sediments that have been dated to about 10m years old. The teeth are believed to come from at least three apes of the same species that lived in what would have been a forested valley at the time. The teeth are close in shape and size to those of modern gorillas, with smaller versions of crests (which help with chewing tough, fibrous material) that are a characteristic of gorilla teeth.

However, Peter Andrews, former head of human origins at the Natural History Museum in London, said the researchers needed more evidence to be sure they had identified a new great ape species. "They're saying an awful lot from an awful little... These structures appear on at least three independent lineages of apes, including gorillas, and they could relate to a dietary shift rather than indicating a new genetic trait. It is stretching the evidence to base a time scale for the evolution of the great apes on this new fossil,"

So this discovery could be a significant discovery forcing us to rethink our very early origins or it could be it could be a false alarm. Such is the way of scientific discovery. It’s still fascinating stuff, though....