Tag Archives: primates

Golf ball.

Primate males with more ornamentation seem to have smaller testes, a new study finds

Showing off takes stones for male primates. Small ones, it turns out.

Golf ball.

Pppppffff, show-off!
Image via Pixabay.

Gird your loins, ladies and gentlemen, because today we have a rather peculiar (but still interesting, and quite amusing) study to talk about. Hailing from the The University of Western Australia and the University of Zurich, the paper reports that flashy male primates tend to have smaller gonads, while their more average-looking counterparts sport larger ones. It all seems to be a product of how male primates handle social hierarchies and reproductive strategies.

Two kinds of primates

Dr. Cyril Grueter, a primatologist from UWA’s School of Human Sciences and a co-author of the present paper, says that male primates tend to live in relatively high-competition environments. They also pretty much all want the same thing: to impress (and impregnate) the females.

“But not all of them can have what they want,” he adds. “So how do they succeed? Well, next to simply fighting, they can produce so-called ‘badges of status’; showy ornaments that help their bearers control access to females by intimidating other males.

“And if males cannot keep others off their females, they can win by producing a lot of sperm to swamp those from their rivals.”

The study focused on primates because of their “tremendous variation in both testicle size and male ornamentation,” a press release accompanying the paper explains. Dr. Grueter seconds this view, saying that some primates they looked at in the study had testicles no larger than a peppercorn, while others’ could easily pass for tennis balls. Pun intended.

Pretty surprisingly, however, the team found that there’s a consistent link between different indicators of male virility throughout primate species. The team compiled data from over 100 species of primate (including humans) to show that ornamentation seems to come at the expense of testicle size and sperm production ability.

“We found the same thing with ornamentation – some species sport flamboyant accoutrements such as beards, manes, capes, and cheek flanges, and various shades of colour in their faces and fur,” he said.

“Others are pretty drab and look more like your Mr Average.”

In blunter terms, showy primate males have smaller testes. Dr. Grueter jokes that the “finding clearly shows that you can be well-adorned or well-endowed, but it’s hard to be both”. This either-or approach likely comes down to economics, the team suspects: it simply takes up too much energy to invest in both reproductive strategies.

The findings also tie in with some of Grueter’s past research. In a study published in the journal  Evolution and Human Behavior back in 2015, he and his team reported that male primates have developed more ostentatious ‘ornaments’ or ‘badges’ (such as beards in humans, cheek flanges in orangutans and so on) to help them navigate big, multilevel societies.

Such elements could help males attract the attention — and affections — of females while also helping them deal with male competition in a more direct way. Male rhesus macaques (Macaca mulatta) with darker red faces receive more ‘come-ons’ from females during the mating season, the team reported in that study, while men with beards could be seen as more aggressive and dominant than those without beards — helping them intimidate competitors and attract women drawn to seemingly powerful men. That paper also suggested these badges are particularly useful for males in large, complex groups, as proxies to show dominance or rank.

“When you live in a small group where everyone knows everyone because of repeated interactions, there is no need to signal quality and competitiveness via ornaments,” Greuter explained at the time.

“In large groups where individuals are surrounded by strangers, we need a quick reliable tool to evaluate someone’s strength and quality, and that’s where these elaborate ornaments come in. In the case of humans, this may also include phenotypic extensions such as body decoration, jewellery and prestige items.”

So, primate ladies in the audience, take heed: flashy males may catch your eye… but there’s really only enough energy to pursue a single reproductive strategy at a time.

The paper “Sexual ornaments but not weapons trade off against testes size in primates” has been published in the journal Proceedings of the Royal Society B: Biological Sciences.

Lion-tail Macaque eating a fruit.

Eating fruit may have given primates their big brains, paving the way for social structures

A New York University doctoral student has found evidence that would support an alternate explanation of why primates evolved such big brains — the secret isn’t social interaction, but a diet rich in fruit, she says.

Lion-tail Macaque eating a fruit.

Lion-tail Macaque eating a fruit.
Image credits Tambako The Jaguar / Flickr.

Primates don’t have big fangs, menacing claws, or imposing horns to fight off predators or take on pray. They rely on a more subtle, but much more powerful, ace up their sleeve. Namely, primates distinguish themselves from almost all other animals through their big brains. They keep primates safe, let them do all sorts of smart things like use tools or go to the Moon, and help them navigate the ever-busy social life with grace.

Why the long brain?

But it’s not clear why they have evolved these big brains in the first place. The prevailing theory today is the social brain hypothesis, according to which primates evolved a bigger brain because they don’t have claws or horns — they needed to bunch up and work together for safety, which required more processing power to understand all the subtleties of social interaction.

A new study comes to offer another, and somewhat unexpected, explanation to the big brain: fruit. Alex DeCasien, a doctoral student in biological anthropology at the New York University initially set out to see how the brains of monogamous primates stacked up to those of more promiscuous species. She and her team collected data on the social life and diets of over 140 species throughout all four primate groups — monkeys, apes, lorises, and lemurs — and crunched all the data to see which features were most likely to associate with bigger brains.

Her results show that it’s neither monogamy nor promiscuity that best predicts the size of a primate’s brain. Neither did other measures of social complexity, such as average group size. The best indicator of brain size, the team explains, is diet — specifically whether a specie’s diet is fruit or leaf-based.

Squirrel monkey eating fruit.

Rumor has it that eating fruit also correlates well with maniacal cackles and evil in small packages. Like this guy.
Image credits Tambako The Jaguar / Flickr.

But the paper has come under some fire from one of the original authors of the social brain theory. Robin Dunbar, an evolutionary psychologist at the University of Oxford in the United Kingdom, said that while more nutrients do allow for a bigger brain, they can’t become a selective evolutionary pressure by themselves — meaning that better food makes bigger brains possible but not necessary, so they aren’t needed.

He agrees that primates who primarily consume fruits can get a whole lot more energy from their diets than leaf eaters. The nutrients in leaves are locked behind thick cell walls that are hard to break down, so leaf-eating primates have to lie around for hours redirecting all their energy towards digestion. Fruits, on the other hand, are much more nutritious and easily digested, meaning they release more energy for less investment and a lot of that extra energy gets gobbled up by the brain.

“In order to have a bigger brain, you have to have a change in diet,” Dunbar said.

But comparing diet with social life is like “comparing apples and oranges,” he argued. His main gripe with DeCasien’s theory is that it doesn’t offer a reason for which all that energy goes towards a bigger brain and not bigger muscles, for example. The social theory does link those two together, he further explains. Living together helps keep the primates safe and gives easy access to mates, two very powerful selective pressures. But it also requires a bigger, more capable brain to navigate and keep track of increasingly complex social structures — so there’s also an evolutionary incentive to invest energy in bigger brains.

“[Diet and sociality] are not alternative explanations,” Dunbar concludes. “They are complementary explanations.”

DeCasien in turn argues that fruit-eaters need more cognitive oomph to get dinner than their counterparts. If you’re a prima.. If you’re a wild leaf-eating primate chances are there will be leaves all around you, so getting dinner should be as easy as stretching out a hand to get them. Fruit-eaters on the other hand have to remember where the best fruits can be found at different times of the year, so their brain needs to be able to handle a map and a calendar app at the same time. They also need good problem solving skills, or even the capacity to use tools, since fruits can be hard to reach or protected by wooden shells or spines.

Floss silk tree bark.

Go on. Take my fruit. I dare you.
Image credits Brisbane City Council / Flickr.

So it makes sense to assume that smarter primates (those with bigger brains) could get more fruit — creating an evolutionary pressure for bigger brains. This explanation could even go so far as to making social life irrelevant to brain size, even make it a by-product of fruit diets — with bigger brains, primates could now handle social interaction so they bunched up.

Still, DeCasien admits that the answer likely isn’t as clear cut. Diets may have initially promoted brain-growth, enabling social groups — and those groups in turn then drove further evolution.

“It’s definitely impossible to tease apart at some point,” she says.

Problem is, you can’t really pick apart evolutionary pressures and beneficial physiological changes in a study such as this — because again, correlation doesn’t imply causation. But seeing the huge impact cooked food has made for humanity, it’s obvious that diet has a role to play in evolution. Whether it’s the hand that points the way or one that simply shapes in the details will have to be answered by future research.

The paper “Primate brain size is predicted by diet but not sociality” has been published in the journal Nature Ecology & Evolution.

Wild cats’ brains evolve to a different tune than those of primates, study finds

Different needs may guide big cats’ brains to differ from those of other mammals, a new Michigan State University study found.

Image credits Skeeze / Pixabay.

The large frontal brain lobes we see in monkeys, humans, or other social mammals are believed to be so well developed because they lead an intricate social life. But cheetahs are also social creatures, and their frontal lobes are relatively small. Some solitary felines, on the other hand, have pretty large frontal lobes.

Sharleen Sakai, professor of psychology and neuroscience at the Michigan State University and lead author of a paper looking into the issue, says his finding suggest there are multiple other factors besides sociality that influence brain anatomy in carnivores.

“Studying feline brain evolution has been a bit like herding cats,” said Sakai.

“Our findings suggest the factors that drive brain evolution in wild cats are likely to differ from selection pressures identified in primate brain evolution.”

Sakai’s lab wanted to understand which factors shaped carnivore brains into the organs we see today. So, the team looked at 75 wild feline skulls comprising 13 different species, which they obtained from museum collections, including those at MSU. After giving them CT scans, the researchers used specialized software to “fill in” the skulls with brain tissue. In the end, they obtained a pretty accurate measurement of each species’ brain volume.

One theory for the large brains humans and primates show is the effect of sociality. Because living in a group rather than alone is more demanding on the brain — keeping track of who’s who, one’s place in the group, and the overall group dynamics and rules requires a lot of dedicated processing power — we have evolved larger, “social brains“, particularly developed in the frontal cortex area.

“We wanted to know if this idea, called the ‘social brain’ hypothesis, applied to other social mammals, especially carnivores and, in particular, wild cats,” Sakai said.

Of the 13 examined species of felines, 11 are solitary and 2 are social (lions and cheetahs). The team found that overall brain size didn’t differ, on average, between the solitary and social species of wild cats. The size of the brain’s area which includes the frontal cortex, however, did.

Female lions had the largest frontal cortexes, which makes sense — female lions are possibly the most social of all wild cats. They form closely-knit groups to protect their cubs, hunt, or defend territory. Males, who may mostly live solitary lives and take a dominant position in a pride for only a few years at a time, had smaller frontal cortexes. This difference may reflect the lionesses’ adaptation to a much more social life, with more “brain” to process through the needs of life in the pride.

Cheetahs, the other social cat examined, had the smallest overall brains and the smallest frontal cortex of the wild cats. The team thinks that they evolved smaller brains as they weigh less and require less energy — both pretty handy traits if you’re a predator relying on speed to catch prey.

“Cheetah brain anatomy is distinctive and differs from other wild cats,” Sakai said. “The size and shape of its brain may be a consequence of its unusual skull shape, an adaptation for high-speed pursuits.”

Another surprising find was that the leopard‘s frontal lobes are relatively large. Although this species is solitary, it’s also very flexible and adaptable — both behaviors being associated with larger brain size and processing ability in other species.

The full paper “Big Cat Coalitions: A Comparative Analysis of Regional Brain Volumes in Felidae” has been published in the journal Frontiers in Neuroanatomy.

Study suggests that primates prefer alcohol in their nectar

Image credit David Haring

Image credit David Haring

From the pubs and bars that line the city streets to the fermented nectars, spas and fruits in nature, alcohol is everywhere. Much like humans, primates have adapted alcohol into their diets and – also like humans – evolved the ability to digest it quickly. Now, a new study shows that the strange aye-aye, a prosimian primate that possesses a genetic mutation also seen in humans and African great apes that accelerates alcohol digestion, prefers alcohol beverages.

The aye-aye is a nocturnal lemur originating from Madagascar with an evolutionary lineage that spans back almost 70 million years. They are some of the strangest creatures on the planet, with unique bony fingers that they use to find grubs in dying tree trunks.

“Aye-ayes are essentially primate woodpeckers,” said Nathaniel Dominy, a professor of anthropology and biological sciences at Dartmouth. “So it is puzzling that they can digest alcohol so efficiently.”

During the wet season, however, the proportion of tree nectar in the aye-aye diet increases. If this nectar is fermented, than a boosted alcohol digestion would start to make more evolutionary sense.

The team tested alcohol preference in two aye-ayes using a nectar-simulation solution of sucrose, as well as the preference of one slow loris, which is the only primate currently known to consume fermented nectar in the wild.

The alcohol concentrations in the nectar-simulation solutions were low, ranging from none to five percent in order to reflect the levels typically found in nature. For each liquid treatment there were two controls of tap water, each placed in a circular array of small-recessed containers in a round resin outdoor table. Positioning was randomized and the experimenters were blind to the contents of the containers during behavioral data collection to eliminate any kind of observational bias.

Each of the two aye-ayes conducted the trial once a day for a total of 15 days and 30 trials between the two of them. Conversely, the slow loris participated in one trial per day over five days for a total of five trials.

The results revealed that the aye-ayes could not only discriminate between the tap water containers and those with alcohol, they adjusted their intake according to the varying alcohol concentrations in the liquid treatments. In addition, they preferred the treatments with the highest concentrations of alcohol and continued to search the high concentration containers long after they were empty.

Data from the slow loris trials was too limited for any statistical results, but discrimination and preference patterns were almost identical.

The results highlight the idea that fermented foods were an important part of our ancestors’ diets and suggest that the genetic mutation that increases alcohol digestion seen in humans, African great apes and aye-ayes is linked to the consumption of fermented fruits on the forest floor.

“This project has definitely fueled my interest in human evolution,” said Samuel Gochman, a student from Dartmouth University and lead author of the study. “Our results support the idea that fermented foods were important in the diets of our ancestors.”

Journal Reference: Alcohol discrimination and preferences in two species of nectar-feeding primate. 20 July 2016. 10.1098/rsos.160217

Comparison of footfall sequence in primate (baboon, above) and nonprimate (cat, below). Footfall sequence is depicted numerically, beginning with the right hind limb in each animal. The primate is walking in diagonal sequence (RH-LF-LH-RF), and the nonprimate is walking in lateral sequence (RH-RF-LH-LF). Image from Muybridge E (1887) . Animal Locomotion: An Electro-photographic Investigation of Consecutive Phases of Animal Movements, 1872-1885: 112 Plates. Published under the auspices of the University of Pennsylvania.

The family that walks on all-fours does not constitute reverse evolution

bbc_walk_on_all_four

In 2006 , the BBC aired a fascinating documentary that featured that featured a family of five siblings from a remote corner of Turkey that remarkably solely moved about by walking on all fours. Many anthropologists of the time saw this behavior as evidence of reverse evolution and sought to extensively study the phenomenon in order to gain insights on how human bipedal locomotion can to be. Researchers from the US, however, claim they have proof that the family that walks on all-fours, as they’re commonly referred to in literature, simply adapted to an unfortunate neurological syndrome and their behavior does not constitute backward evolution.

Here’s the documentary:

At the time of their discovery, Uner Tan of Cukurova University asserted that the family members’ condition,  called Uner Tan Syndrome (UTS), acts like a model for reverse evolution, mimicking the way non-human primates, like monkeys or apes, move about. This view, while it gained considerable traction, has been repeatedly countered by studies which found people with UTS simply adapted to the impaired ability to walk bipedally.

[RELATED] Early hominds started walking on two legs because of shifting geology

The team, comprised of researchers at Northeast Ohio Medical University, University of Arizona, New York University, carefully analyzed footage of 518 quadrupedal walking strides and compared them to walking patterns of healthy adults who were asked to move around a laboratory on all fours. More than 98% of participants, whether they were asked to walk on all fours or were forced to because of UTS, walked in lateral sequences – they placed a foot down, then the corresponding hand from the same side, before performing the same sequence on the other side. Non-human primates, however, use what’s called a diagonal quadruped sequence,  in which they put down a foot on one side and then a hand on the other side, continuing that pattern as they move along.

“Although it’s unusual that humans with UTS habitually walk on four limbs, this form of quadrupedalism resembles that of healthy adults and is thus not at all unexpected,” says  Liza Shapiro, an anthropologist at The University of Texas at Austin. “As we have shown, quadrupedalism in healthy adults or those with a physical disability can be explained using biomechanical principles rather than evolutionary assumptions.”

Comparison of footfall sequence in primate (baboon, above) and nonprimate (cat, below). Footfall sequence is depicted numerically, beginning with the right hind limb in each animal. The primate is walking in diagonal sequence (RH-LF-LH-RF), and the nonprimate is walking in lateral sequence (RH-RF-LH-LF). Image from Muybridge E (1887) . Animal Locomotion: An Electro-photographic Investigation of Consecutive Phases of Animal Movements, 1872-1885: 112 Plates. Published under the auspices of the University of Pennsylvania.

Comparison of footfall sequence in primate (baboon, above) and nonprimate (cat, below). Footfall sequence is depicted numerically, beginning with the right hind limb in each animal. The primate is walking in diagonal sequence (RH-LF-LH-RF), and the nonprimate is walking in lateral sequence (RH-RF-LH-LF). Image from Muybridge E (1887) . Animal Locomotion: An Electro-photographic Investigation of Consecutive Phases of Animal Movements, 1872-1885: 112 Plates. Published under the auspices of the University of Pennsylvania.

The researchers believe initial research in favor of reverse evolution was misguided by confusing  diagonal sequence with diagonal couplets. Sequence refers to the order in which the limbs touch the ground, while couplets (independent of sequence) indicate the timing of movement between pairs of limbs. People with UTS more frequently use diagonal couplets than lateral couplets, but the sequence associated with the couplets is almost exclusively lateral.

“Each type of couplet has biomechanical advantages, with lateral couplets serving to avoid limb interference, and diagonal couplets providing stability,” Shapiro says. “The use of diagonal couplets in adult humans walking quadrupedally can thus be explained on the basis of biomechanical considerations, not reverse evolution.”

Findings were reported in the journal PLOS ONE.

Shape of the hand and foot in two primate species. The fingers are represented independently (colour coded) in the primate somatosensory cortex (SI). By contrast, the representations of the toes are fused, with the exception of the big toe in humans. (Credit: Image courtesy of RIKEN)

Which came first: the dexterous hand or the agile foot?

Shape of the hand and foot in two primate species. The fingers are represented independently (colour coded) in the primate somatosensory cortex (SI). By contrast, the representations of the toes are fused, with the exception of the big toe in humans. (Credit: Image courtesy of RIKEN)

Shape of the hand and foot in two primate species. The fingers are represented independently (colour coded) in the primate somatosensory cortex (SI). By contrast, the representations of the toes are fused, with the exception of the big toe in humans. (Credit: Image courtesy of RIKEN)

A common assumption in human evolution is that our early ancestors first developed bipedal locomotion and only then did they developed dexterous hands capable of using tools, since these were free to be used no longer being required for walking. A new research by a team of Japanese scientists proved this long-standing assumption wrong, however, after they used high-end laboratory techniques to show that dexterous hands evolved before agile feet used in locomotion.

The research is particularly interesting because it combines a range of multi-disciplinary techniques and makes use of evolutionary correlations between modern humans and monkeys of today and those from the dawn of our genus. The researchers led by neurobiologist Dr. Atsushi Iriki of the RIKEN Brain Science Institute employed functional magnetic resonance imaging in humans and electrical recording from monkeys to locate the brain areas responsible for touch awareness in individual fingers and toes, called somatotopic maps. These maps showed that both humans and monkeys have discrete neural signatures for single digits in the hand and foot.

[READ MORE] Why human ancestors started walking on two legs

There’s one prominent difference between the monkey and human maps: the human big toe has its own map, while all monkey toes are combined and fused into one single map. These findings suggest that early hominids evolved dexterous fingers when they were still quadrupeds. Manual dexterity was not further expanded in monkeys, but humans gained fine finger control and a big toe to aid bipedal locomotion.

“In early quadruped hominids, finger control and tool use were feasible, while an independent adaptation involving the use of the big toe for functions like balance and walking occurred with bipedality,” the authors explained.

To support these laboratory findings, the researchers showcased the well-preserved hand and feet bones of a 4.4 million year-old skeleton of the quadruped hominid Ardipithecus ramidus, a species with hand dexterity that preceded the human-monkey lineage split. In all, the findings suggest that our early ancestors first developed hand dexterity, critical to tool use, while two-legged locomotion came after as a consequence of adaptive pressures on ancestral quadrupeds for balance control by foot digits.

“Evolution is not usually thought of as being accessible to study in the laboratory,” stated Dr. Iriki, “but our new method of using comparative brain physiology to decipher ancestral traces of adaptation may allow us to re-examine Darwin’s theories.”

The results were reported in a paper published in journal Philosophical Transactions of the Royal Society.

gelade

Primate howl hints towards origins of human speech

gelade

The gelade make strange sounds that biologists keenly describe as being similar to those produced during human speech. (c) Thore Bergman

Scientists have always tried to answer how speech developed in humans or what are its evolutionary mechanisms, a mystery made even more difficult to unravel since none of our close primate relatives has been granted with even the most primitive forms of speech, or so it was thought. Researchers studying the gelada – a primate that closely resembles the baboon – found that its calls show distinct features that mirror those of humans speech.

The call of the gelada, which live only in the remote mountains of Ethiopia, sounds like a cross between a yodel and a baby’s gurgle. Upon closer inspection, there’s a lot more to it than just noise though.

The lead author Dr Thore Bergman, from the University of Michigan in the US, said: “Geladas make vocalisations that have some speech-like properties – it’s the first time that that has been shown in a non-human primates.”

Monkey and apes can only make the most basis noises, however a study published last year suggests that despite non-human primates lack the vocal anatomy required to produce sophisticated sounds, a behaviour known as “lip-smacking” shared by many could be related to speech. The term describes the rapid movement of the jaws, lips and tongues in much the same way that humans do as they speak.

In addition to lip-smacking, however, the gelade have been shown to also produce complex, undulating sounds whose patterns closely resembles those found in human vocalization.

“In [human] speech, the onset of a syllable is loud and then there are quiet parts inbetween. If you were to look at a waveform where you see how speech gets louder and quieter across time, the time between those peaks happens at a fairly predictable frequency of 3Hz to 8Hz across different languages.

“The same thing happens with the gelada ‘wobbles’ – the periodicity has the same frequently,” Dr Thore Bergman explained.

The researchers recollect how amazingly similar to human-speech the gelade hauls are.

“I would find myself frequently looking over my shoulder to see who was talking to me, but it was just the geladas,” he recalled. “It was unnerving to have primate vocalizations sound so much like human voices.”

The researchers do not yet know how the gelade use their hauls to communicate with each other if the case in the first place, yet their findings offer solid hints as to how the evolution of speech might work – a combination of “lip-smacking” and vocalisations.

The study is published in the journal Current Biology.

(c) Ikiwaner/Wikimedia Commons

Origins of alcohol consumption traced back to 10-million-year-old common ancestor

Now, I’m not advocating alcohol consumption, but truth be told most of us take alcohol for granted, and I’m not referring to abusing either. Millions of years ago, our ancestors and primate relatives had a very poor ability of metabolizing ethanol — the alcohol in beer, wine and spirits — and were it not for their pioneering “work”, we humans might have not been able to enjoy alcoholic spirits the way we do today.

(c) Ikiwaner/Wikimedia Commons

(c) Ikiwaner/Wikimedia Commons

Chemist Steven Benner of the Foundation for Applied Molecular Evolution in Gainesville, Fla believes that our first ancestor capable of metabolizing ethanol may have lived 10 million years ago, after him and colleagues reconstructed  alcohol-metabolizing enzymes of extinct primates.

To break down ethanol, humans like most primates use an enzyme called alcohol dehydrogenase 4 or ADH4, for short. Since the enzyme is fairly common through out the esophagus, stomach and intestines, it is the very first line that meets alcohol when a person drinks, and thus is the most important component in breaking down ethanol. However, not all primates have the same working ADH4, as some can’t even effectively metabolize ethanol – poor fellows.

Alcohol consumption: a tradition worth million of years

The researchers analyzed the stretches of DNA referring to ADH4 in 27 modern primate species, including lemurs, monkeys, apes and humans. In the meantime estimates of extinct primates’ enzyme genetic code was made; enzymes that were then rebuilt in the lab and analyzed in order to gain a better understanding of how these work. Equipped with this new found data, the researchers mapped the DNA sequences on a primate family tree in order to see how the genes changed in key points of the tree, like the branching points, typically corresponding to extinct primates.

Their results show that most primate ancestors wouldn’t have been able to metabolize ethanol, however at a certain branching point that lead to the evolution of modern day primates like gorillas, chimps or humans – corresponding to an ancestor that lived roughly 10 million years ago – the enzyme became capable of digesting alcohol. The jump is rather staggering since the enzyme is believed to have been 50 times more efficient than those in earlier ancestors.

Obviously, a catalyst was required and the scientists hypothesize that it was during that time that our tree dwelling ancestors began to explore the ground level more. It is here they might have found fruit fallen from the trees that fermented its sugars into ethanol. Individuals that could metabolize the alcohol in these fruits better than those who didn’t had a better chance at surviving, and thus the enzyme became stronger in generations to come.

But it may be too soon to link metabolizing ethanol with living on the ground, said Jeremy DeSilva, a biological anthropologist at Boston University. “There’s very little fossil evidence from the general time period when humans, gorillas and chimpanzees last shared a common ancestor.”

Benner exposed his idea during a talk at the recent American Association for the Advancement of Science annual meeting. In the meantime, I can’t help myself posting this incredibly hilarious video that shows what effects alcohol has on primates and other animals. Not surprisingly, they don’t behave too differently from our own human debaucheries.

The newly identified species of slow loris, Nycticebus kayan. (c) Shamma Esoof

New slow loris species discovered in Borneo is already threatened

Biologists have identified a new species of small nocturnal primates, part of the slow loris family, in Borneo’s forests. Don’t be fooled by its cute grim though, this tiny critter packs a punch, as its bite is poisonous and can cause harm to humans. Nevertheless, barely as it was discovered, scientists issued a warning to environmental agencies that the new slow loris is threatened with extinction due to habitat loss and trapping.

The newly identified species of slow loris, Nycticebus kayan. (c) Shamma Esoof

The newly identified species of slow loris, Nycticebus kayan. (c) Shamma Esoof

The new species of slow loris, named Nycticebus kayan, like most elusive nocturnal critters, has gone unnoticed because of its lifestyle. Professor Anna Nekaris of Oxford Brookes University in the UK, and Rachel Munds from the University of Missouri in Columbia, US had to survey great patches of forests in Borneo and the Philippines in search for the slow loris.

In the paper published in the journal American Journal of Primatology, the researchers describe the facial traits of the N. kayan that add up to form a sort of mask. The research has revealed there are actually four species of slow loris in the Philippines and Borneo, each with their own, subtly different but distinct head markings. Recently alone, two other slow loris species were identified,  N. bancanus and N. borneanus, which were previously considered subspecies of N. menagensis.

The N. kayan is already is already threatened, unfortunately, at the hands of deforestation and poaching. It’s not its fur or other commodities that makes it attractive for poachers, but its cuteness, which makes it a prime candidate on the illegal pet-trade market in Asia. The N. kayan delivers a fierce blow, being one of the few mammals with a toxic bite, so captive animals often have their canine and incisor teeth pulled out. This puts them at great risk since they can’t chew food properly, ultimately causing death. The toxin is powerful enough to potentially cause fatal anaphylactic shock in people.

 “Unfortunately, in addition to habitat loss to deforestation, there is a booming black market demand for the animals. They are sold as pets, used as props for tourist photos or dismembered for use in traditional Asian medicines,” Munds said.

She added that technological advances had enabled the team to identify it as a separate species. “Historically many species went unrecognised as they were falsely lumped together as one species. While the number of recognised primate species has doubled in the past 25 years some nocturnal species remain hidden to science.”

 

 

 

Required daily feeding time for hominin and great ape species to afford combinations of MBD and total number of brain neurons. Notice that H. heidelbergensis, H. neanderthalensis, and H. sapiens fall well over the viability curve for 8 h/d of feeding if they had a raw foods diet similar to extant nonhuman primates. (c) Fonseca-Azevedo and Herculano-Houzel

Cooking food helped early humans grow bigger brains

The pyramids, art, all of the world’s great inventions, literary works, just about any valuable intellectual work can be traced back to food – cooked food. If you care to go as far back as our very roots, that is. Previous research showed that cooked food made it easier and more efficient for our guts to absorb calories more rapidly, which helped increase the brains of our early ancestors. A new research by neuroscientists at  the Federal University of Rio de Janeiro in Brazil found that humans nowadays would need to eat 9 hours non-stop to get enough energy from unprocessed raw food alone to support our large brains.

“If you eat only raw food, there are not enough hours in the day to get enough calories to build such a large brain,” says Suzana Herculano-Houzel, a neuroscientist at the Federal University of Rio de Janeiro in Brazil who is co-author of the report. “We can afford more neurons, thanks to cooking.”

Humans have roughly three times as many neurons (86 billion) than our close primate cousins, like gorillas (33 billion) or chimpanzees (28 billion). The Brazilian scientists found that the number of neurons is directly linked to brain size, as well as to the amount of energy needed to feed the brain. Thus, humans need brains consume 20% of our body’s energy when resting, compared with 9% in other primates – a hefty cost. This begged the question, however: from where did our ancestors get all this extra energy to grow such a large brain in a relatively short evolutionary time frame?

Required daily feeding time for hominin and great ape species to afford combinations of MBD and total number of brain neurons. Notice that H. heidelbergensis, H. neanderthalensis, and H. sapiens fall well over the viability curve for 8 h/d of feeding if they had a raw foods diet similar to extant nonhuman primates. (c) Fonseca-Azevedo and Herculano-Houzel

Required daily feeding time for hominin and great ape species to
afford combinations of MBD and total number of brain neurons. Notice that
H. heidelbergensis, H. neanderthalensis, and H. sapiens fall well over the
viability curve for 8 h/d of feeding if they had a raw foods diet similar to
extant nonhuman primates. (c) Fonseca-Azevedo and Herculano-Houzel

The answer is cooked food, according to the researchers. Back in the 1990s, Harvard University primatologist Richard Wrangham asserted, in a now famous thesis, that the human lineage embarked on an explosive growth of the brain some 1.6 to 1.8 million years ago when Homo Erectus started cooking food. Wrangham claimed that processed food is more efficiently absorbed in the body, significantly increasing the relative energy intake compared to digesting raw food. Follow-up studies at the time demonstrated that rodents or pythons grow faster and bigger when they eat cooked meat instead of raw meat, and that it takes less energy to digest cooked meat than raw meat.

You’d need to eat raw food for 9 hours without rest in order to get the same energy kick

 A comparison of the frontal lobes (colored) in human and several non-human primate species. The evolutionary relationships among the species are indicated by the connecting lines. Semendeferi and colleagues5 found that human frontal lobes are not disproportionately larger than predicted for a primate brain of its size. (Figure courtesy of K. Semendeferi and H. Damasio from a different  research - Nature Neuroscience  5, 190 - 192 (2002)  doi:10.1038/nn0302-190).

A comparison of the frontal lobes (colored) in human and several non-human primate species. The evolutionary relationships among the species are indicated by the connecting lines. Semendeferi and colleagues5 found that human frontal lobes are not disproportionately larger than predicted for a primate brain of its size. (Figure courtesy of K. Semendeferi and H. Damasio from a different research – Nature Neuroscience 5, 190 – 192 (2002) doi:10.1038/nn0302-190).

For the present research, the neuroscientists calculated how many hours per day humans and other primates need to eat raw food in order to support their current brains and body size. They found that it would take 8.8 hours for gorillas; 7.8 hours for orangutans; 7.3 hours for chimps; and 9.3 hours for our species, H. sapiens. Worth noting is the fact that raw food in this case, refers to that found in the wild, not processed raw food that humans typically prepare with blenders and add protein and other nutrients to.

 “The reason we have more neurons than any other animal alive is that cooking allowed this qualitative change—this step increase in brain size,” she says. “By cooking, we managed to circumvent the limitation of how much we can eat in a day.”

This study shows “that an ape could not achieve a brain as big as in recent humans while maintaining a typical ape diet,” Wrangham says.

Not all researchers are convinced however that cooking food sparked the brain growth explosion of our ancestors. That may very well be so, believes Paleoanthropologist Robert Martin of The Field Museum in Chicago, Illinois, who agrees that the present paper is the first to provide tangible evidence of metabolic limitations, but who goes on to say that whether our ancestors began cooking over a fire later, when the brain went through a second major growth spurt about 600,000 years ago or during H. Erectus is still unclear. The earliest evidence of hominid fire control found thus far has been dated from 800,000 years ago, and  regular use of fire for cooking doesn’t become widespread until more recently.

“Gorillas are stuck with this limitation of how much they can eat in a day; orangutans are stuck there; H. erectuswould be stuck there if they had not invented cooking,” Herculano-Houzel said. “The more I think about it, the more I bow to my kitchen. It’s the reason we are here.”

Findings were published in the journal Proceedings of the National Academy of Sciences

source: ScienceMag

Dead gene is resurrected in humans

This is what researchers believe to be the first true comeback of a gene in the human/great ape lineage; the study was led by Evan Eichler’s genome science laboratory at the University of Washington and the Howard Hughes Medical Institute, and they pointed out that the infection-fighting human IRGM is (as far as we know) the first doomed gene to make a comeback in our own species.

Medical interest sparkled for this gene when scientists discovered that IRGM mutations can lead to an inflammatory digestive disorder known as Crohn’s disease. Also, in the animal world there are significant variations of this gene; for example, mice have 21 Immune-Related GTPases, and most mammals have several. The truncated IRGM gene is one of only two genes of its type remaining in humans.

In this latest study, they reconstructed the evolutionary history of this gene, and they found out that it was eliminated by going to multiple copies to only a single copy in primates, about 50 million years ago. By comparing Old World and New World monkey species suggest that the gene dissappeared in their common ancestor.

Everything went according to plan and the inactive gene was inherited through millions and millions of years of evolution. But then, something totally unexpected happened: the gene started to produce proteins once more. The only evidence they could find for this relied on a retrovirus that was somehow inserted in this ancient genome.

“The IRGM gene was dead and later resurrected through a complex series of structural events,” Eichler said. “These findings tell us that we shouldn’t count a gene out until it is completely deleted.”