Thursday, 20 September 2012

Ancient Tooth May Provide Evidence of Early Human Dentistry (and Bee King)

Beeswaxed Tooth - If you squint hard enough you can
make out the face of a man wearing a wicked mad hat.
Clearly, King of the Bees.

ScienceDaily (Sep. 19, 2012) Researchers may have uncovered new evidence of ancient dentistry in the form of a 6,500-year-old human jaw bone with a tooth showing traces of beeswax filling, as reported Sept. 19 in the open access journal PLOS ONE.

The researchers, led by Federico Bernardini and Claudio Tuniz of the Abdus Salam International Centre for Theoretical Physics in Italy in cooperation with Sincrotrone Trieste and other institutions, write that the beeswax was applied around the time of the individual's death, but cannot confirm whether it was shortly before or after. If it was before death, however, they write that it was likely intended to reduce pain and sensitivity from a vertical crack in the enamel and dentin layers of the tooth.

According to Tuniz, the severe wear of the tooth "is probably also due to its use in non-alimentary activities, possibly such as weaving, generally performed by Neolithic females."

Evidence of prehistoric dentistry is sparse, so this new specimen, found in Slovenia near Trieste, may help provide insight into early dental practices.

"This finding is perhaps the most ancient evidence of pre-historic dentistry in Europe and the earliest known direct example of therapeutic-palliative dental filling so far," says Bernardini.

Journal article: Federico Bernardini, Claudio Tuniz, Alfredo Coppa, Lucia Mancini, Diego Dreossi, Diane Eichert, Gianluca Turco, Matteo Biasotto, Filippo Terrasi, Nicola De Cesare, Quan Hua, Vladimir Levchenko. Beeswax as Dental Filling on a Neolithic Human Tooth. PLoS ONE, 2012; 7 (9): e44904 DOI: 10.1371/journal.pone.0044904

Wednesday, 19 September 2012

Caws and Effect (AMA)

"Reddit, what have I gotten myself into?"

Alex Taylor takes your questions on Reddit (AMA)

After the warm response yesterday that Redditors gave Alex Taylor and colleagues paper, "New Caledonian crows reason about hidden causal agents", the social media website have invited him to participate in an 'Ask Me Anything' (AMA).

Get your crow cognition questions ready for Alex Taylor as he takes on Reddit /science/ in an AMA (Ask Me Anything) - Sept, 19, 23:00 GMT


Tuesday, 18 September 2012

The mysterious, "You don't understand me!", workings of the adolescent brain

"Oh such juicy brains there are here at TED....mmmm"

(TED, 18, Sept, 2012) - Why do teenagers seem so much more impulsive, so much less self-aware than grown-ups?

Cognitive neuroscientist Sarah-Jayne Blakemore compares the prefrontal cortex in adolescents to that of adults, to show us how typically “teenage” behaviour is caused by the growing and developing brain.

Crows can 'reason' about causes, a recent study finds

Curious crow is curious

(BBC Nature, 18, Sept, 2012) - Tool-making crows have the ability to "reason", say scientists.

In an experiment, researchers found that crows were more likely to forage when they could attribute changes in their environment to a human presence.

This behaviour may suggest "complex cognition", according to a study published in the Proceedings of the National Academy of Sciences.  Until now the ability to make inferences based on causes has been attributed to humans but not animals.

The study was a collaboration between researchers from the University of Auckland, New Zealand, the University of Cambridge, UK and the University of Vienna, Austria.

In their experiment eight wild crows used tools to remove food from a box.  Inside the enclosure there was a stick and the crows were tested in two separate series of events that both involved the stick moving.

In one instance a human entered the hide and the stick moved. In the other, the stick still moved but no human entered.  On the occasions when no human was observed entering the hide, the crows abandoned their efforts to probe for food using a tool more frequently than they did when a human had been observed.

According to the scientists, the study proved that crows attributed the stick's movement to human presence.

The results indicated that neither age nor sex was a predictor of the behaviour with juveniles, males and females displaying the same behaviour.  Scientists said that the kind of "reasoned inference" shown by the New Caledonian crows under these controlled conditions could also be utilised in the wild to anticipate danger or food.

The study is the first to suggest that animals have the ability to make reasoned inferences, although scientists added that the phenomenon could be more common among animals than previously thought.

Journal reference: New Caledonian crows reason about hidden causal agents -

Monday, 17 September 2012

Crows can remember and differentiate human faces

"I know I know you"
 - The Crow (1994)

(New Scientist, Sept, 10, 2012) - You can run from a crow that you've wronged, but you can't hide. Wild crows remember human faces in the same way that mammals do.

Crows can distinguish human faces and remember how different people treated them, says John Marzluff of the University of Washington in Seattle.

To work out how the crows process this information, Marzluff had members of his team wear a latex mask as they captured 12 wild American crows (Corvus brachyrhynchos). The crows learned to associate the captor's mask with this traumatic experience. While in captivity, the crows were fed and looked after by people wearing a different mask.

After four weeks, the researchers imaged the birds' brains while they were looking at either the captor or feeder mask. The brain patterns looked similar to those seen in mammals: the feeder sparked activity in areas involved in motivation and reward, whereas the captor stimulated regions associated with fear.

The result makes sense, says Kevin McGowan of Cornell Lab of Ornithology in Ithaca, New York. Crows don't mind if humans are in their habitat – but they need to keep a close eye on what we do.

Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1206109109

Size Does Matter. Brain Size!

Big brains, but all they
want to talk about is mackerel. 

(Discover Magazine, Sept, 11, 2012) - Every whale and dolphin evolved from a deer-like animal with slender, hoofed legs, which lived between 53 and 56 million years ago. 

Over time, these ancestral creatures became more streamlined, and their tails widened into flukes. They lost their hind limbs, and their front ones became paddles. And they became smarter.  Today, whales and dolphins – collectively known as cetaceans – are among the most intelligent of mammals, with smarts that rival our own primate relatives.

Now, Shixia Xu from Nanjing Normal University has found that a gene called ASPM seems to have played an important role in the evolution of cetacean brains. The gene shows clear signatures of adaptive change at two points in history, when the brains of some cetaceans ballooned in size. But ASPM has also been linked to the evolution of bigger brains in another branch of the mammal family tree – ours. It went through similar bursts of accelerated evolution in the great apes, and especially in our own ancestors after they split away from chimpanzees.

It seems that both primates and cetaceans—the intellectual heavyweights of the animal world—could owe our bulging brains to changes in the same gene. “It’s a significant result,” says Michael McGowen, who studies the genetic evolution of whales at Wayne State University. “The work on ASPM shows clear evidence of adaptive evolution, and adds to the growing evidence of convergence between primates and cetaceans from a molecular perspective.”

For decades, we’ve known that similarities between primate and cetacean intelligence run deep. For a start, both groups have members with unusually big brains. We humans have brains that are 7 times bigger than you’d expect for an animal of their size. The equivalent number is 2-3 for chimps and some monkeys, and 4-5 for some dolphins.

Over the last decade, scientists have identified seven genes that are linked to primate brain size. They’re called MCPH1 to MCPH7 (ASPM is the fifth in the line). Faults in these genes can lead to microcephaly – a developmental disorder characterised by a debilitatingly small brain.

McGowen had already shown that, unlike in humans, MCPH1 doesn’t neatly correlate with brain size in cetaceans. Xu wanted to see if ASPM would be more interesting. He sequenced the gene in fourteen species of cetaceans, from the bottlenose dolphin to the minke whale. He then compared these to known sequences from 18 other mammals, including several primates and the hippopotamus (the closest living relative to cetaceans).

Xu found that ASPM went through two periods of strong positive selection – where beneficial new versions of the gene spread through a population. The first coincides with the point when toothed whales (like sperm whale and dolphins) split away from the baleen whales (like blue, fin and humpback whales). Their brains got bigger. The second period marks the split of the toothed whales into the delphinoids (including all oceanic dolphins and porpoises) and all the others. The delphinoids’ already big brains got bigger still.

Xu also found signatures of positive selection within the ASPM genes of primates, but not in any other mammal groups. During their history, both groups must have experienced some evolutionary pressures that meant bigger brains suddenly became advantageous. We can only speculate what these might have been. For cetaceans, the toothed whales evolved to navigate with echolocation, and may have needed a larger brain to process the information from all the returning echoes. The delphinoids may owe their larger brains to the mental demands of living in large, complex social groups. (Both hypotheses have been on the cards for some time, and Xu’s ASPM discovery doesn’t provide a smoking gun for either.)

What does ASPM actually do? The gene is activated in neuroblasts, the embryonic cells that eventually divide into neurons. It helps to create structures in dividing cells that send a full complement of DNA into each daughter. If ASPM isn’t working properly, the neuroblasts cannot divide evenly, and brains get smaller. It’s not clear how the reverse happens – how changes in ASPM lead to bigger brains, but it’s now clear that this has happened in at least two mammal groups.

Xu found certain mutations that were associated with the bigger brains of toothed whales, and others that are associated with the even bigger brains of delphinoids. What these mutations did is anyone’s guess, and something that will take a lot of experimental work to uncover.

Here’s one critical nugget, though: they’re different to the changes you see in primates. The same gene may have enlarged the brains of both groups, but it did so in different ways. And undoubtedly, other genes were also involved.

(To close, here’s possibly my favourite ever example of convergent evolution, which also involves cetaceans. Toothed whales and some bats both use echolocation, and their abilities depend on the same changes to the same gene – Prestin. This was discovered at the same time by two independent groups of researchers, one led by Yang Liu and the other by Ying Li!)

Reference: Xu, Chen, Cheng, Yang, Zhou, Xu, Zhou & Yang. 2012. Positive selection at ASPM gene coincides with brain size enlargements in cetaceans. Proc Roy Soc B.