Who wants to live forever? Who dares to love forever, when even naked mole rats must die?
Granted, that wouldn’t make a very good lyric, even for Highlander 2, but after several weeks of back and forth articles about whether multi-cellular life is doomed to perish from a sort of internal evolutionary race that inevitably favors non-cooperating selfish cells over good team (and organ) players, Science has a nice article on the one mammal … the one very strange mammal … that seems to have this aging thing under control.
Naked mole rats are weird, wrinkly — and possibly stay young forever.
In the world of animal models, naked mole rats are the supermodels. They rarely get cancer, are resistant to some types of pain, and can survive up to 18 minutes without oxygen. But perhaps their greatest feat, a new paper suggests, is that they don't age.
That paper, from Comparative biologist Rochelle Buffenstein at Google biotech startup Calico, represents more than 30 years of research on the little communal not-really-rats-or-moles. What Buffenstein found is that the chance of a mole rat dying was the same in year one as it was in year five. And ten. And thirty. In fact, barring accidents and disease, naked mole rats may just have this immortality thing licked.
In 1825, British mathematician Benjamin Gompertz found that the risk of dying rises exponentially with age; in humans, for instance, it doubles roughly every 8 years after the age of 30. The law applies to all mammals after adulthood, says João Pedro De Magalhães, a gerontologist at the University of Liverpool in the United Kingdom.
But Buffenstein did not see this trend in her lab animals. After they reached sexual maturity at 6 months of age, each naked mole rat’s daily chance of dying was a little more than one in 10,000. It stayed the same the rest of their lives and even went down a little, Buffenstein reports this week in elife. “To me this is the most exciting data I’ve ever gotten,” says Buffenstein. “It goes against everything we know in terms of mammalian biology.”
There’s a chance that this data could be somewhat screwed by the simple fact that most mole rats aren’t under decades long observation. That is, yes Buffenstein’s lab group is still hale and hearty, but maybe that’s because their life span happens to be 50. Or 31. They may explode into a puff of smoke tomorrow. But for an animal that size to live so long is already extraordinary. Similar sized animals usually have life spans that can be counted on a single hand.
Why do the pink and wriggly live so long? It’s not yet clear. They have a high level of molecules that help proteins fold correctly — and misfolded proteins have been the villains of a lot of pieces in ASR. So maybe the secret of mole rats long and toothy life is simply keep things neat.
Now, let’s use our relatively fleeting lives to look at some more articles below the line...
Brain size evolved ahead of brain shape.
When scientists are trying to determine the relative braininess of human ancestors, the usual method is simply measuring brains by volume. But since we know that different parts of the brain have different specialties — even if there is a good deal of flexibility and overlap — the shape of the brain is also an interesting indicator.
Within the last decade, fossils from North West Africa have revealed that the species Homo sapiens goes back about twice as long as we previously thought, with several specimens over 320,000 years in age that wave received solid H. sapiens stamps. But now a group from the Max Planck Institute for Evolutionary Anthropology in Germany has taken a look inside the skulls of these and a large number of other ancient examples of apparently modern humans, and what they’ve found is a bit surprising.
Our data show that, 300,000 years ago, brain size in early H. sapiens already fell within the range of present-day humans. Brain shape, however, evolved gradually within the H. sapiens lineage, reaching present-day human variation between about 100,000 and 35,000 years ago.
So our 300K BCE ancestors already had brains as large as people you pass on the street, but those brains were arranged a bit differently. The presence of ancient modern humans has always been a bit of a puzzle not because there’s a reason to believe humans are particularly young as a species, but because the oldest of those apparently modern people didn’t seem to be very modern when it came to the tools they made or the art they didn’t make. In fact, it’s not until around 80,000 years ago that modern humans seem to start to make significant advances over previous human species, and only around 40-50,000 years ago that the first evidence of symbolic thinking — in the form of representational art — begins to appear.
For decades, that change in behavior has been treated as something of a mystery, usually accompanied by the phrase “brain size didn’t change over this period.” But size … isn’t everything. And maybe those humans who first appeared around 300,000 years ago weren’t us after all.
Early stone tools from India push back timeline for human cultures in Asia.
It’s not just the age of modern humans that been pushed back in the last few years. Just last month came publication of a paper indicating that modern humans apparently left Africa — at least for a short period — tens of thousands of years earlier than had previously been known. And now, from a group of Indian archaeologists, comes news of more advanced stone tools in India that predate previous sites — by a lot.
Luminescence dating at the stratified prehistoric site of Attirampakkam, India, has shown that processes signifying the end of the Acheulian culture and the emergence of a Middle Palaeolithic culture occurred at 385 ± 64 thousand years ago (ka), much earlier than conventionally presumed for South Asia. …
At Attirampakka, the gradual disuse of bifaces, the predominance of small tools, the appearance of distinctive and diverse Levallois flake and point strategies, and the blade component all highlight a notable shift away from the preceding Acheulian large-flake technologies.
Those eye-popping dates associated with an Asian site would usually have people thinking about Homo erectus, which reached Asia at least 1.7 million years ago. Both the complexity of these tools suggests modern humans. And if modern humans were in India over 300,000 years ago … that blows up the dating for the exodus of H. sapiens from Africa.
And … honestly, while this could be extremely exciting, I’m not that excited yet. Because when you’re dealing with stone tools and no remains, at a site that appears to have been in use for almost 200,000 years, dates may not be as solid as they seem. Also, the quality of stone tools often seems considerably higher to their discoverers than it does to anyone else, see any number of pre-Clovis America sites for an example.
Six months from now, if this holds up, there’s serious rethinking to do. Including bringing up some previously big, and seriously misused, theories about the origins of modern humans.
Looking to the plants for answers on climate over 11,000 years.
What do you do when climate models give one answer about past temperatures, and ocean sediment disagrees? Go to the pollen records for a tie breaker. And the winner is…
Here we show that temperatures reconstructed from sub-fossil pollen from 642 sites across North America and Europe closely match simulations, and that long-term warming, not cooling, defined the Holocene until around 2,000 years ago.
The climate models seem to hold up. From the end of the last glacial period until about 2,000 years ago, the Earth had been slowly warming. Then, about 2,000 years ago, a modest period of cool began. And then … we reversed that cooling in a matter of decades.
The pollen data suggests that the interpretations of past temperatures from sediment cores need more thinking, but for the climate models that matched the data, it’s a good indication that they’re able to project temperatures into the past, and perhaps into the future.
A five year treatment window isn’t long enough for ER-positive breast cancer.
Treatment for ER-positive breast cancer includes taking that lower the activity of the estrogen receptor. Generally, this treatment continues for five years after initial treatment, and women who are disease free at the end of this period stop taking the ER lowering drugs.
Unfortunately, that turns out to be a bad idea. A New England Journal of Medicine followed up on 62,923 women treated for breast cancer in this way, and found that the rate of recurrence actually didn’t drop over the whole twenty year period of the study. So dropping the drugs after five years was an invitation to another round of recurrence, diagnosis, and active treatment.
Remarkably, the most powerful determinants of the risk of recurrence were those originally used to grade the aggressiveness of the primary cancer — the diameter of the tumour and the number of lymph nodes containing cancerous cells, which indicates whether the primary disease had spread at the start of treatment. However, even among women with small, node-negative tumours, the risk of metastasis was about 10% over the 15-year period.
That means that 90 percent of those with ER-positive breast cancer would not see recurrence after the five year period. But it may also indicate that at least some level of drug use might be advisable over a longer period, especially for those who had larger, more widespread tumors at the outset.
An objective measure for creativity?
Being able to hang a number on someone’s creativity seems almost self-contradictory, but a diverse group of researchers — including a pair of physicists — suggest that the key to measuring creativity can be found in one of those terms that people often throw out when they’re thinking about anything but creativity.
We propose a quantitative measure of flexibility based on the robustness of semantic memory networks to attack, assuming that the higher robustness, the higher the flexibility of the network. We show how the semantic network of high creative individuals is more robust to attack, thus more flexible. This is a direct computational investigation on flexibility of semantic memory and creativity. Our approach can be applied to more general questions such as high-level cognitive capacities and clinical populations suffering from atypical thought processes.
Is that just semantic? Maybe … or maybe that’s creative.
Measuring creativity by brain imaging.
Where on group is looking for a way to objectively test and grade creativity, another group is out to measure it by looking at brain activity.
We identified a brain network associated with creative ability comprised of regions within default, salience, and executive systems—neural circuits that often work in opposition. Across four independent datasets, we show that a person’s capacity to generate original ideas can be reliably predicted from the strength of functional connectivity within this network, indicating that creative thinking ability is characterized by a distinct brain connectivity profile.
The measures of activity were done with functional magnetic resonance imaging. The number of people tested and the correlation produced does make it seem like they’re onto something significant — assuming that they’re able to measure creativity using other methods adequately.