Drinking just a couple of beers a day can still cause problems for your brain, scientists have suggested.

While heavy drinking is known to be associated with poor brain health, few studies have examined the effects of moderate drinking on the brain.

This prompted a team of UK researchers to investigate whether moderate alcohol consumption has a beneficial or harmful association - or no association at all - with brain structure and function.

Drawing on a 30-year study tracking 550 healthy men and women, the scientists from Oxford University and University College London found that higher alcohol consumption over that period was associated with increased risk of hippocampal atrophy - a form of brain damage that affects memory and spatial navigation.

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While those consuming more than 30 units a week were at the highest risk compared with abstainers, even those drinking moderately - 14 to 21 units per week - were three times more likely to have hippocampal atrophy compared with those who drank nothing.

Higher consumption was also associated with poorer "white matter integrity", something critical for efficient cognitive functioning, and faster decline in language fluency, including how many words beginning with a specific letter could be generated in one minute.

The authors of the paper, just published in the BMJ (British Medical Journal), pointed out that it was an observational study, so no firm conclusions can be drawn about cause and effect.

But they added their findings could still have important potential public health implications for a large sector of the population.

"Our findings support the recent reduction in UK safe limits and call into question the current US guidelines, which suggest that up to 24.5 units a week is safe for men, as we found increased odds of hippocampal atrophy at just 14-21 units a week, and we found no support for a protective effect of light consumption on brain structure," they write.

"Alcohol might represent a modifiable risk factor for cognitive impairment, and primary prevention interventions targeted to later life could be too late."

We're 100,000 years older than we think

This adult mandable was found among 300,000-year-old remains of ancient Homo sapiens at the Jebel Irhoud archeological site in Morocco. Photo / Jean-Jacques Hublin, MPI-EVA, Leipzig
This adult mandable was found among 300,000-year-old remains of ancient Homo sapiens at the Jebel Irhoud archeological site in Morocco. Photo / Jean-Jacques Hublin, MPI-EVA, Leipzig

New fossil finds have pushed the origins of our species back by 100,000 years - and have also revealed what was on the menu for our oldest-known Homo sapiens ancestors 300,000 years ago.

It included plenty of gazelle meat, with the occasional wildebeest, zebra and other game and perhaps the seasonal ostrich egg.

An international research team has just reported the latest findings from the Jebel Irhoud archaeological site in Morocco, which has been well known since the 1960s for its human fossils and for its Middle Stone Age artefacts.

Scientists have recovered 16 new Homo sapiens fossils - including skulls, teeth, and long bones of at least five individuals - along with stone tools and animal bones.

Intriguingly, dating has revealed flints to be approximately 300,000 years old - 100,000 years earlier than the previously oldest Homo sapiens fossils.

But there were further clues about what our ancient ancestors were snacking on at the time.

Professor Teresa Steele, a paleoanthropologist at the University of California, sifted through hundreds of fossil bones and shells, identifying 472 of them to species as well as recording cut marks and breaks indicating which ones had been food for humans.

Most of the animal bones came from gazelles.

Among the other remains, were those of hartebeests, wildebeests, zebras, buffalos, porcupines, hares, tortoises, freshwater molluscs, snakes and ostrich egg shells.

Small game was a small percentage of the remains: "It really seemed like people were fond of hunting."

Cuts and breaks on long bones indicate that humans broke them open, probably to eat the marrow, she said.

Leopard, hyena and other predators' fossils were among the finds, but Steele found little evidence that the non-human predators had gnawed on the gazelle and other prey.

The findings supported the idea that Middle Stone Age began just over 300,000 years ago, and that important changes in modern human biology and behaviour were taking place across most of Africa then.

"In my view, what it does is to continue to make it more feasible that North Africa had a role to play in the evolution of modern humans."

The incredible see-through frog

A recently discovered species from Amazonian Ecuador, is able to fully expose its heart thanks to the transparent skin stretching all over its chest. Photo / Jaime Culebras and Ross Maynard
A recently discovered species from Amazonian Ecuador, is able to fully expose its heart thanks to the transparent skin stretching all over its chest. Photo / Jaime Culebras and Ross Maynard

Some of us like to wear our hearts on our sleeves: but scientists have just found a weird frog that carries its heart on its skin.

The recently discovered species from Amazonian Ecuador is able to fully expose its heart thanks to the transparent skin stretching all over its chest.

The glassfrog, named Hyalinobatrachium yaku, can also be distinguished by the relatively large dark green spots at the back of its head and the foremost part of the body, along with a characteristic long call.

Their reproductive behaviour is also odd: males were often reported to call from the underside of leaves and look after the egg clutches.

A team of researchers led by Ecuadorian scientist Dr Juan M Guayasamin reported in open access journal ZooKeys that the frog likely had a broad distribution, stretching into Peru.

Major threats facing it included oil extraction, water pollution, road development, habitat degradation and isolation.

"Glassfrogs presumably require continuous tracts of forest to interact with nearby populations, and roads potentially act as barriers to dispersal for transient individuals," the researchers wrote.