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Olorgesailie Basin: the dig site spans an area of 65 square kilometres

This is according to a series of papers published today in Science.

The results come from an archaeological site in Kenya’s rift valley. “Over one million years of time” is represented at the site, according to Rick Potts from the Smithsonian Institution, who was involved in the studies.

There are also signs of developments in toolmaking technologies.

Environmental change may have been a key influence in this evolution of early Homo sapiens in the region of the Olorgesailie dig site.

The world turned upside down

Early humans were in the area for about 700,000 years, making large hand axes from nearby stone, explained Dr Potts.

“[Technologically], things changed very slowly, if at all, over hundreds of thousands of years,” he said.

Then, roughly 500,000 years ago, something did change.

A period of tectonic upheaval and erratic climate conditions swept across the region, and there is a 180,000 year interruption in the geological record due to erosion.

It was not only the landscape that altered, but also the plant and animal life in the region – transforming the resources available to our early ancestors.

When the record resumes, the way of life of these early humans has completely changed.

“The speed of the transition is really remarkable,” Dr Potts said. “Sometime in that [gap] there was a switch, a very rapid period of evolution.”

The obsidian road

New tools appeared at this time – small, sharp blades and points made from obsidian, a dark volcanic glass.

This technology marks the transition to what is known as the Middle Stone Age, explained Dr Eleanor Scerri from the University of Oxford.

Rather than shaping a block of rock, into a hand axe, humans became interested in the sharp flakes that could be chipped off. These were mounted on spears and used as projectile weapons.

Where 98% of the rock previously used by people in the Olorgesailie area had come from within a 5km radius, there were no sources of obsidian nearby.

People were travelling from 25km to 95km across rugged terrain to obtain the material, and “interacting with other groups of early humans over that time period”, according to Dr Potts.

This makes the site the earliest known example of such long distance transport, and possibly of trade.

(l to r) Hand axes, obsidian sharps and colour pigments discovered at the site

There is additional evidence that the inhabitants, who would likely have lived in small groups of 20-25 people, also used pigments like ochre. It is unclear whether these were merely practical or had a ritual social application.

Dr Marta Mirazon Lahr from the University of Cambridge said that being able to “securely date” the continuous occupation of the site using argon techniques on volcanic deposits “makes Olorgesailie a key reference site for understanding human evolution in Africa during [this period]”.

Human origins

Dr Scerri, who was not involved in the studies, emphasised that they are valuable in implying that “Middle Stone Age technology emerged at the same time in both eastern and northwestern Africa.”

Prof Chris Stringer from the Natural History Museum agrees.

“This makes me think that the Middle Stone Age probably already existed in various parts of Africa by 315,000 years ago, rather than originating in one place at that time and then spreading,” he said.

While the behaviours exhibited at the Kenya site are characteristic of Homo sapiens, there are as yet no fossils associated with this time period and location.

The oldest known Homo sapiens fossils were discovered in Morocco, and are dated to between 300,000 and 350,000 years old.


Any ad executive will tell you that sex sells. But why? Do sexy images stimulate our biological urges, somehow motivating us to buy products? Or do marketers merely exploit and perpetuate our cultural obsession with sexual imagery? Do people want the beauty, wealth and power celebrities have, and use the products they endorse in the hope of achieving these same qualities?

These explanations are plausible, but my colleagues and I have a new one, based on decades of work comparing the behavior and neurobiology of decision-making in monkeys and people: Our brains have been fine-tuned by evolution to prioritize social information, and this laser focus on others profoundly shapes our decisions.

As early as the 1870s, companies like Pearl Tobacco and later, W. Duke & Sons, employed social advertising, showcasing nude or partially exposed women on posters and trading cards. Although the images had no direct link to the products, sales increased. A century and a half later, it seems impossible to escape sexual imagery in advertising. The same is true for celebrities in marketing campaigns—actors, musicians, athletes, even politicians and business leaders. These celebrities often don’t even use the products they advertise, yet the method still seems to work.

Our brains have circuits specialized for identifying, remembering and inferring the mental states of others so we can predict their behavior and make good decisions. In other words, we’re built to deal with people. But we’re not alone in this connection. Many species of monkeys and apes—our closest living relatives—also live in large, complex, dynamic societies. Behavioral studies show that, like us, these primates identify others, track prior encounters, empathize with friends and relatives, and make inferences about individuals’ mental states.

For people and monkeys alike, it’s important to find a good mate, make powerful allies and avoid potential threats. Paying close attention to social cues can improve these choices. In fact, both men and male monkeys are exquisitely sensitive to indications of female fertility. Men rate ovulating women as more attractive, and tip more for lap dances by fertile women. Similarly, male rhesus macaques prefer images of females with artificially reddened faces and hindquarters, coloration that predicts ovulation and sexual receptivity.

Women and female monkeys are also sensitive to clues about male quality, although what we know about that is based on fewer studies. A woman’s preference shifts toward more masculine faces—broader jaw, wider-set but smaller eyes—during ovulation. Female macaques, when ovulating, tend to mate with higher-ranking males and prefer those with reddened faces caused by a testosterone surge. Other studies found that both people and monkeys pay more attention to high-status individuals and are more likely to follow their gaze.

According to economics, we can quantify how much someone values something—coffee, a magazine—by how much he or she will pay for it. In our latest work, we developed an assessment, dubbed the “pay-per-view” test, to measure subconscious value of visual images. In the experiment, monkeys had the option to forego juice or food for a glimpse at a picture of another monkey. People could choose whether to accept a smaller cash reward to peek at a picture of another individual.

Our findings were striking. Male college students paid slightly more money to view an attractive woman than an unattractive one, losing several dollars during the experiment. Female students were much less motivated to see attractive men. Monkeys of both genders valued sex and status, accepting less food or juice to see images of monkey genitalia and faces of high-status males. In contrast, they required extra food or juice to look at faces of low-status males.

Based on these findings, it’s clear that monkeys and humans value information about sex and status so much that it can replace rewards like food, juice and money. Strong parallels between the two suggest shared brain mechanisms at work.

To test this idea, we used fMRI to scan the brains of male students in two circumstances: one, while they viewed female faces of varying attractiveness, the other while money was either deposited or withdrawn from their study stipend. The sight of attractive faces strongly activated a network of brain areas previously implicated in processing rewards—including the orbitofrontal cortex, ventromedial prefrontal cortex, and medial and ventral striatum—and neural activity increased with increasing attractiveness. The same happened with monetary rewards and losses. We believe this network computes economic “utility,” a person’s internal desire for or satisfaction with a good or service, thought to underlie decisions.

To determine the physiological basis of these signals, we measured individual brain cell activity in monkeys. Some fired strongly when male monkeys chose to see female genitalia, a high-status male face, or a large juice reward, but fired less when they chose low-status faces or small juice rewards. Specific brain cells reacted to images of faces and genitals but not juice, indicating the brain’s reward system possesses dedicated hardware for identifying and prioritizing key social information.

Can these discoveries help explain the power of sex and status in advertising? In theory, ads that associate sex or status with specific brands or products activate the brain mechanisms that prioritize social information, and turning on this switch may bias us toward the product.

To test this idea, we exposed male rhesus macaques to logos of household brands like Nike and Pizza Hut paired with a social image (e.g., female genitalia, high-status male face) or the same image with pixels rearranged to make it unrecognizable but retain the same brightness, contrast, and color, salient cues that could draw attention to a stimulus. Monkeys received a sweet treat for touching the screen after the ad, then had the choice between brands paired with a social image or its scrambled version.

Our advertising campaign was remarkably effective. Monkeys developed preferences for brands linked with sex and status. Both males and females preferred logos paired with sexual cues and the faces of high-status monkeys. And the more often male monkeys saw sexual advertisements, the more they preferred the brands. Sound familiar? Even monkeys, it seems, can be persuaded to choose a brand through social advertising.

Given the nearly identical specializations of brain reward circuits to prioritize social information in monkeys and people, is it any wonder that sex and status sell?

Chunks of clay excavated from Iron Age grain bins in South Africa. Early farmers burnt their clay huts and grain storage buildings in times of drought as part of a cleansing ritual, unknowingly locking the magnetic properties of the minerals in the clay into place.

A flip in Earth’s magnetic field may be brewing. And if it is, an electromagnetic blob deep under southern Africa is likely to be ground zero for the change.

New research using clays burned in cleansing rituals by Iron Age farmers finds that over the past 1,500 years, an electromagnetic anomaly in the Southern Hemisphere has waxed and waned, with the magnetic field in the region weakening and strengthening. This weirdness may presage a gradual reversal in the magnetic field, so that magnetic north moves to the South Pole and vice versa. (A flip-flop of this sort last occurred 780,000 years ago.)

The study suggests that the magnetic field under southern Africa may not just be weird today, study co-author John Tarduno, who researches the Earth’s magnetism at the University of Rochester in New York, told Live Science. It may be a longstanding hotspot for changes in the global magnetic field.


The planet’s magnetic field is generated by the churning of liquid iron in the core. Without the field, life on the planet would be much different, if not impossible: This invisible shield protects the Earth’s surface from deadly cosmic radiation.

Right now, the field is undergoing a weakening, and no one is sure why. The South Atlantic Anomaly, a region of the magnetic field that stretches from South Africa to Chile, is particularly weak, Tarduno said, so scientists have become interested in figuring out what might be going on in the core underneath that area.

The problem is that before about 160 years or so ago, with the advent of magnetic observatories and (eventually) satellite observations, there weren’t many records of what the magnetic field looked like in the Southern Hemisphere, Tarduno said. Ninety percent of the data that does exist comes from the northern half of the planet. To start to rectify that disparity, Tarduno and his team excavated clays from the Limpopo River Valley of Zimbabwe, South Africa, and Botswana. In times of drought hundreds to thousands of years ago, Bantu-speaking farmers would burn down their clay huts and grain bins in ritualistic ceremonies. Unbeknown to these ancient farmers, the fire heated the magnetic minerals in the clay and locked into place a record of the strength and orientation of the field at that time. Now, researchers can study those properties to find out what the magnetic field was doing at that moment in time.


The excavations unearthed these burnt clays as long ago as A.D. 425, Tarduno said, providing the longest record yet of the magnetic field in southern Africa. The data show that the magnetic field experienced sudden directional shifts between A.D. 400 and 450, and then again between A.D. 750 and 800. Between about A.D. 1225 and 1550, the field noticeably weakened. The first two shifts might also indicate a weakened field, Tarduno said, but more research is needed to determine the magnetic intensity in those time frames. The researchers reported their findings Feb. 15 in the journal Geophysical Research Letters.

What these shifts suggest is that what is going on in the Southern Hemisphere’s magnetic field today may have happened before, Tarduno said.

The field shifts may have to do with underlying processes churning deep beneath the Earth’s surface, Tarduno said. In recent years, scientists have documented a weird patch of magnetic field below southern Africa at the boundary between the core and the mantle, where the polarity of the field is reversed.

“That patch may be largely responsible for the decreasing magnetic field,” Tarduno said.

The patch is like an eddy in a stream, he said. As for what causes the eddy, it may be something odd about the mantle right above the core in that location, he said. The mantle under southern Africa is unusual, and possibly both hotter and denser than surrounding mantle, he said.

“We think that is causing there to be changes in the flow of the iron [in the core] as it enters this region,” Tarduno said.

That could mean that southern Africa is the origin for magnetic field reversals, Tarduno said, though there’s no guarantee that the field will flip now — the weakening could also dissipate, as it has in centuries past.

Even if the field doesn’t reverse, though, the weakening itself could have societal implications, Tarduno said.

“These are not of the nature of disaster movies. That’s not the point,” he said. Instead, a weakening field could let more cosmic radiation hit the Earth, making infrastructure like the power grid more susceptible to geomagnetic storms and even changing atmospheric chemistry so that more UV rays could sneak through, causing increased risk for skin cancer in humans.

“It’s definitely something that we need to keep an eye on,” Tarduno said.

By Tereza Pultarova

About 4 percent of the people on Earth experience a mysterious phenomenon called synesthesia: They hear a sound and automatically see a color; or, they read a certain word, and a specific hue enters their mind’s eye. The condition has long puzzled scientists, but a small new study may offer some clues.

The study, published March 5 in the journal Proceedings of the National Academy of Sciences, offers insight into what might be happening in the brains of people with synesthesia.

Previous “studies of brain function using magnetic resonance imaging confirm that synesthesia is a real biological phenomenon,” said senior study author Simon Fisher, director of the Max Planck Institute for Psycholinguistics in the Netherlands. For example, when people with synesthesia “hear” color, brain scans show that there’s activity in the parts of the brain linked to both sight and sound, he said. (Not all people with the condition “hear” sights, however; the condition can also link other senses.)Indeed, the brains of people with synesthesia previously have been shown to be more connected across different regions than the brains of people whose senses are not cross-linked, Fisher told Live Science. The question, however, was what causes this different brain wiring, he said.

To answer that question, Fisher and his team looked to genetics.

Synesthesia frequently runs in families, so the researchers decided to look for genes that might be responsible for the development of the condition. They chose three families, in which multiple members across at least three generations had a specific type of synesthesia, the so-called sound-color synesthesia, meaning that hearing sounds evokes perceptions of colors. Typically, a specific sound or musical tone is consistently associated with a specific color for people who have this type of synesthesia. However, different members of a single family can see different colors when hearing the same sound, Fisher said.

The scientists used DNA sequencing to study the participants’ genes, Fisher said. Then, to identify genes that might be responsible for the condition, the scientists compared the genes of family members with synesthesia to the genes of family members without it, he said.

But the findings didn’t yield a straightforward result: “There was not a single gene that could explain synesthesia in all three families,” Fisher said. Instead, “there were 37 candidate variants,” or possible gene variations, he said.

Because the study included only a small number of people, there wasn’t enough data to single out the specific genes, of the 37 possibilities, that played a role in synesthesia. So, instead, the scientists looked at the biological functions of each gene to see how it could be related to the development of the condition. “There were just a few biological themes that were significantly enriched across the candidate genes identified,” Fisher said. “One of those was axonogenesis, a crucial process helping neurons get wired up to each other in the developing brain.” Axonogenesis refers to the development of neurons.

This is consistent with prior findings of altered connectivity in brain scans of people with synesthesia, Fisher said. In other words, the genes identified in the study play a role in how the brain is wired, offering a potential explanation for why the brains of people with synesthesia appear to be wired differently.

Researchers from St. Jude Children’s Research Hospital have discovered that inhibiting an enzyme called cyclin-dependent kinase 2 (CDK2) protects mice and rats from noise- or drug-induced hearing loss. The study, which will be published March 7 in the Journal of Experimental Medicine, suggests that CDK2 inhibitors prevent the death of inner ear cells, which has the potential to save the hearing of millions of people around the world.

According to the World Health Organization, 360 million people worldwide, including 32 million children, suffer from hearing loss caused by congenital defects or other factors. These factors include infectious disease, use of certain medicines, or exposure to excessive noise. Yet, there are currently no FDA-approved drugs to prevent or treat hearing loss.

A team of researchers led by Dr. Jian Zuo screened over 4,000 drugs for their ability to protect cochlear cells from the chemotherapy agent cisplatin. Cisplatin is used to treat a variety of cancers but causes irreversible hearing loss in up to 70% of patients.

Zuo and colleagues identified multiple compounds that protected cochlear cells from cisplatin, several of which are already approved to treat other conditions. Three of the ten most effective compounds were inhibitors of an enzyme called CDK2. One of these CDK2 inhibitors, kenpaullone, was more effective than four other compounds that are currently in clinical trials for treating hearing loss.

Injecting kenpaullone into the middle ear protected both mice and rats from cisplatin-induced hearing loss. Moreover, kenpaullone also protected the hearing of mice to noise as loud as 100 dB. “Given that 100-dB noise is in the range of noise insults commonly experienced by people in our society, kenpaullone could have significant clinical application in treating noise-induced hearing loss,” says Zuo.

In the case of cisplatin-induced hearing loss, kenpaullone appears to protect hair cells by preventing CDK2 from stimulating the production of toxic reactive oxygen species from the cells’ mitochondria.

“The robust protection conferred by one-time local delivery of kenpaullone suggests that CDK2 inhibitors may transform the clinical prevention and treatment of cisplatin- and noise-induced hearing loss in patients,” Zuo says. “Modifications of the treatment regimens, additional optimization of the delivery methods via the use of hydrogels, and structural modifications of the compounds via medicinal chemistry could ensure even better results with CDK2 inhibitors in treating hearing loss in humans.”

By Rafi Letzter

“Magic” mushrooms seem to have passed their genes for mind-altering substances around among distant species as a survival mechanism: By making fungus-eating insects “trip,” the bugs become less hungry — and less likely to feast on mushrooms.

That’s the upshot of a paper published Feb. 27 in the journal Evolution Letters by a team of biologists at The Ohio State University and the University of Tennessee.

The researchers studied a group of mushrooms that all produce psilocybin — the chemical agent that causes altered states of consciousness in human beings — but aren’t closely related. The scientists found that the clusters of genes that caused the ‘shrooms to fill themselves with psilocybin were very similar to one another, more similar even than clusters of genes found in closely related species of mushrooms.

That’s a sign, the researchers wrote, that the genes weren’t inherited from a common ancestor, but instead were passed directly between distant species in a phenomenon known as “horizontal gene transfer” or HGT.

HGT isn’t really one process, as the biologist Alita Burmeister explained in the journal Evolution, Medicine and Public Health in 2015. Instead, it’s the term for a group of more or less well-understood processes — like viruses picking up genes from one species and dropping them in another — that can cause groups of genes to jump between species.

However, HGT is believed to be pretty uncommon in complex, mushroom-forming fungi, turning up much more often in single-celled organisms.

When a horizontally transferred gene takes hold and spreads after landing in a new species, the paper’s authors wrote, scientists believe that’s a sign that the gene offered a solution to some crisis the organism’s old genetic code couldn’t solve on its own.

The researchers suggested — but didn’t claim to prove — that the crisis in this case was droves of insects feasting on the defenseless mushrooms. Most of the species the scientists studied grew on animal dung and rotting wood — insect-rich environments (and environments full of opportunities to perform HGT). Psilocybin, the scientists wrote, might suppress insects’ appetites or otherwise induce the bugs to stop munching quite so much mush’.


People have evolved to sleep much less than chimps, baboons or any other primate studied so far.

A large comparison of primate sleep patterns finds that most species get somewhere between nine and 15 hours of shut-eye daily, while humans average just seven. An analysis of several lifestyle and biological factors, however, predicts people should get 9.55 hours, researchers reported recently in the American Journal of Physical Anthropology. Most other primates in the study typically sleep as much as the scientists’ statistical models predict they should.

Two long-standing features of human life have contributed to unusually short sleep times, argue evolutionary anthropologists Charles Nunn of Duke University and David Samson of the University of Toronto Mississauga. First, when humans’ ancestors descended from the trees to sleep on the ground, individuals probably had to spend more time awake to guard against predator attacks. Second, humans have faced intense pressure to learn and teach new skills and to make social connections at the expense of sleep.

As sleep declined, rapid-eye movement, or REM — sleep linked to learning and memory (SN: 6/11/16, p. 15) — came to play an outsize role in human slumber, the researchers propose. Non-REM sleep accounts for an unexpectedly small share of human sleep, although it may also aid memory (SN: 7/12/14, p. 8), the scientists contend.

“It’s pretty surprising that non-REM sleep time is so low in humans, but something had to give as we slept less,” Nunn says.

Humans may sleep for a surprisingly short time, but Nunn and Samson’s sample of 30 species is too small to reach any firm conclusions, says evolutionary biologist Isabella Capellini of the University of Hull in England. Estimated numbers of primate species often reach 300 or more.

If the findings hold up, Capellini suspects that sleeping for the most part in one major bout per day, rather than in several episodes of varying durations as some primates do, substantially lessened human sleep time.

Nunn and Samson used two statistical models to calculate expected daily amounts of sleep for each species. For 20 of those species, enough data existed to estimate expected amounts of REM and non-REM sleep.

Estimates of all sleep times relied on databases of previous primate sleep findings, largely involving captive animals wearing electrodes that measure brain activity during slumber. To generate predicted sleep values for each primate, the researchers consulted earlier studies of links between sleep patterns and various aspects of primate biology, behavior and environments. For instance, nocturnal animals tend to sleep more than those awake during the day. Species traveling in small groups or inhabiting open habitats along with predators tend to sleep less.

Based on such factors, the researchers predicted humans should sleep an average of 9.55 hours each day. People today sleep an average of seven hours daily, and even less in some small-scale groups (SN: 2/18/17, p. 13). The 36 percent shortfall between predicted and actual sleep is far greater than for any other primate in the study.

Nunn and Samson estimated that people now spend an average of 1.56 hours of snooze time in REM, about as much as the models predict should be spent in that sleep phase. An apparent rise in the proportion of human sleep devoted to REM resulted mainly from a hefty decline in non-REM sleep, the scientists say. By their calculations, people should spend an average of 8.42 hours in non-REM sleep daily, whereas the actual figure reaches only 5.41 hours.

One other primate, South America’s common marmoset (Callithrix jacchus), sleeps less than predicted. Common marmosets sleep an average of 9.5 hours and also exhibit less non-REM sleep than expected. One species sleeps more than predicted: South America’s nocturnal three-striped night monkey (Aotus trivirgatus) catches nearly 17 hours of shut-eye every day. Why these species’ sleep patterns don’t match up with expectations is unclear, Nunn says. Neither monkey departs from predicted sleep patterns to the extent that humans do.

C.L. Nunn and D.R. Samson. Sleep in a comparative context: Investigating how human sleep differs from sleep in other primates. American Journal of Physical Anthropology. Published online February 14, 2018. doi:10.1002/ajpa.23427.