Smilodon bringing down MegatheriumSabre-toothed cats had weak bites – a new comparison of Smilodon‘s skull with a modern lion’s shows that the cat probably didn’t run up and bite its prey with those teeth. Probably it brought prey down with a full-body tackle (it had extra strong claws) and then used the famous teeth to make the kill once it had the animal pinned. At least, that’s the latest theory.

Velociraptor’s ‘killing’ claws were for climbing – I’m just ruining all the prehistoric artists’ conceptions today, aren’t I? Analyses of velociraptor claws shows they weren’t sharp enough to disembowel prey, but were strong enough to hold the dinosaur’s weight as it climbed trees.

Kids, even babies, judge others based on skin color – and we exacerbate the problem by keeping the subject taboo. The author writes of his own son: “Katz’s work helped me to realize that Luke was never actually colorblind. He didn’t talk about race in his first five years because our silence had unwittingly communicated that race was something he could not ask about. … we started to overhear one of his white friends talking about the color of their skin. They still didn’t know what to call their skin, so they used the phrase ‘skin like ours.’ And this notion of ours versus theirs started to take on a meaning of its own.”

Swine flu vaccine: Too little, too late (SciAm article, first half available online) – When you’re trying to make enough flu vaccine, boosting production with new methods and adjuvants is at odds with safety and testing (and the potential for lawsuits). The author seems to think litigation is the problem; but if people are suing because they’ve been harmed by the vaccine, wouldn’t it be more correct to say safety is the problem? Deciding how much risk is appropriate is a tough question.

Jell-O shots in adolescence lead to gambling later in life – When you want to study alcohol and risky behavior in rats, do it right! Yes, they really fed the rats jell-o shots, and taught them to gamble.

You little bastard, you've killed us all (pic of toddler licking a pig)A single dose of H1N1 (swine flu) vaccine may be enough, something of a surprise because initial reports from the CDC said it might have to be a two-shot vaccine. That means twice as many people can be vaccinated with the available doses. There was a swine flu shot available in 1976, and people vaccinated or exposed back then (or in 1918!) seem to be protected against this year’s strain. Seasonal flu immunity somehow “primes” H1N1 immunity even though the seasonal flu shot doesn’t, by itself, confer full immunity to H1N1. Bottom line: get a seasonal flu shot (available now) and a single dose of H1N1 vaccine (available in October).

Placebos are getting more effective. If your new drug doesn’t perform any better than a sugar pill, does that mean it’s useless? Some already-approved drugs perform just as badly, even though they stacked up well against placebos when they were first tested. Meanwhile, placebos are useful for more than just testing: “The fact that even dummy capsules can kick-start the body’s recovery engine became a problem for drug developers to overcome, rather than a phenomenon that could guide doctors toward a better understanding of the healing process and how to drive it most effectively.” How do placebos work, anyway? Can you get around anti-doping rules by giving an athlete fake steroids? Can you even really compare today’s Prozac trial results to the originals, given our changing understanding of depression? Good questions in this article from Wired.

Skim milk isn’t automatically better than full-fat, something I’ve been trying to tell people for years. “‘Probably most people who think of themselves as nutrition-savvy would be astonished to learn that evidence of whole milk’s being a ticket to an early grave is conspicuous by its absence,’ says food historian Anne Mendelson in Milk: The Surprising Story of Milk Through the Ages.” Also notable is the type of fat in milk from pastured (grass-fed) cows – more omega-3’s and less of the supposedly “bad” fats.

Will my son be born late, like I was? OK, so this isn’t a national news item but rather something of personal interest. I was two weeks late myself. A study of 77,000 Norwegians found that “Gestational age of the child at birth increased on average 0.58 days for each additional week in the father’s gestational age (95% confidence interval 0.48-0.67) and 1.22 days for each additional week in the mother’s gestational age (1.21-1.32).” Meanwhile a Danish study suggests that gestation length is 23-30% genetic (but they didn’t find a paternal component).

Midnight snacks pack on the pounds. The research, done in rats and involving high-fat foods, isn’t exactly ready for sweeping extrapolation. But I liked the article for this quote specifically: “‘How or why a person gains weight is very complicated, but it clearly is not just calories in and calories out,’ says Fred Turek, professor of neurobiology and physiology at Northwestern University and director of the Center for Sleep and Circadian Biology.” (Contrary to popular belief, people are not bunsen burners.)

Brain differences between men and women aren’t necessarily hard-wired – finally, somebody making sense on this subject. A team at the U of Iowa found that the Straight Gyrus (SG) of the brain is larger in women and seems to correlate with interpersonal skills. But! They also compared SG size to a test of gender, in the personality sense – are you very masculine or very feminine? – and found it correlated better with gender than with biological sex. They also found that the relationship was reversed in children – boys had the larger SG. So do women have naturally better social skills or is that a skill they develop over time, resulting in brain changes? For once, somebody isn’t willing to jump to a conclusion.

(The writer of this article, Lise Eliot, has written a book on how differences between boys’ and girls’ brains are shaped by culture: “Boys are not, in fact, ‘better at math’ but at certain kinds of spatial reasoning. Girls are not naturally more empathetic; they’re allowed to express their feelings. By appreciating how sex differences emerge—rather than assuming them to be fixed biological facts—we can help all children reach their fullest potential.”)

People 32,000 years ago may have spun flax into twine (this is the same stuff as the fabric linen). We don’t know what the threads were used for, but speculation is rampant – clothing to keep warm? Rope to tie sharp things to sticks and make weapons? Or, um, nothing? “It’s possible individual flax fibers blew into the ancient cave, got buried and then became twisted during microscopic analyses,” says Harvard archaeologist Irene Good, who isn’t impressed with these fibers but told Science News that people probably did make some kind of textiles around that era. Ancient pottery (around 26,000 years ago) sometimes includes imprints of nets and ropes.

Late Blight’s genome published – the fungus that is wiping out tomato crops across the Northeast US this year (and that caused the Irish potato famine way back when) may owe its success to highly variable effector genes buried in its “junk” DNA. (“Junk” DNA is never junk, people. We just don’t always know what it does.)

Brown spots in bananas glow blue in UV light. The color change, from degrading chlorophyll, probably attracts insects (lots of animals can see in UV) but is also interesting to scientists as a marker of cell death.

How long food keeps in the fridge – a chart from the new FoodSafety.Gov website. Marion Nestle says, “If we can’t have a single food agency, we can at least have a single food safety site. Now if Congress would just pass some decent food safety laws…”

I’m going to try to make this a recurring thing. Five things I thought were interesting this week:

Factory-farming frogs is now possible (sort of) but still seems like a bad idea. “Just over half the marsh frogs survived three years of intensive farming, whereas only 5 to 8 per cent of the pool and edible frogs did.” Doesn’t sound very humane to me. The upside is supposed to be protecting wild frog populations in Asia from overharvesting. But is this really a good solution? One expert says: “it may be better to simply harvest frogs sustainably in the wild rather than building elaborate, energy-intensive farms that rely on fish meal.” To quote another: “I hear frogs’ legs taste like chicken. Eat that and leave the frogs alone.”

But Genetically “pain-free” animals would make abusive farming practices ethically OK! “I’m offering a solution where you could still eat meat but avoid animal suffering,” says a philosopher who published a paper on the subject this week. This ignores the idea that physical pain is the only kind of suffering that matters. Let me tell you, if I had to live in a battery cage, I would be pretty miserable with or without my Nav1.7 gene.

Lefties may have been rare in Victorian England. While currently 11% of British people are left-handed, only 3% of Victorians waved at movie cameras with their left hand. (The modern control was a Google images search of people waving.) In the Victorian clips, older folks were slightly more likely to wave with the left hand, so the researchers concluded that lefties were a dying breed that, later, bounced back.

Female fruit flies prefer to keep sex short. This is surprising (to the researchers) because male flies have pinchers and other nasty ways of supposedly keeping the females from getting away. It seems all kinds of sex research includes the assumption that the males are in charge and females are passive – and that assumption always breaks down as soon as researchers start looking into it. Best quote, about the methodology: “The team propped up the dead [female] insects—Weekend at Bernie’s-style—to convince the males that they were still alive and ready for sex.” (They mated longer with dead females than with ones that could get away.)

The Manahatta Project aims to reconstruct what the island looked like before it became the heart of New York City. National Geographic reports that Eric Sanderson, an ecologist at the Wildlife Conservation Society, compared old maps and modern GPS readings to reconstruct what the island was like in 1609. (Although the article doesn’t mention, the actual click-and-zoom map includes Lenape settlements and their likely uses of land. It’s not like the place was unsettled.)

Bonus links! Improve your life with science!

navigating - photo by Somewhat Frank on FlickrA new book asks the question, Why do we get lost? I think the more interesting question is, how do we know where we are?

When I was growing up in Munhall I remember being so confused about the layout of the neighborhood that I gave up trying to make sense of it. If I turned left out of my driveway, I could take a certain route through a certain part of town and end up at school. But if I went down my street the complete opposite direction, and passed through a different part of town, I’d end up at the same place.

(Years later, I found out why: my street was shaped like a squiggly horseshoe. When I walked my dog around the block, the block was not square or triangular but rather shaped like an “S”. No wonder I was confused.)

my neighborhood

But even without a mental map, I got around just fine by recognizing landmarks and street names. Now, several groups of scientists are suggesting that humans navigate by landmarks, while other animals use geometry.

Hamsters, toads, and spiders can all navigate like homing pigeons: take the critter away from home by any route you please, and she’ll fly, or crawl, straight back. According to Jack Loomis at UC Santa Barbara, people do badly on a simplified version of this test; and William Warren at Brown found that people could navigate by landmarks through a maze that, geometrically, couldn’t possibly exist. (The maze was a virtual world with invisible “wormholes”).

But are we really so bad at geometric navigation? A recent study looked at the question of whether people who are lost end up walking in circles. The answer: only if they are blindfolded or have no other cues. Test subjects walking around the Sahara, with only shadows from the sun for guidance, did a decent job of walking in a straight line – even though the sun moved during their long hike.

direction - photo by Kulbowski on FlickrMeanwhile, blindfolded people, asked to walk through a field, wandered wildly but didn’t always prefer circular directions. (You wouldn’t know it, though, from all the headlines of “We really do walk in circles.” Only sometimes! Not even most of us!) The authors figured that “sensory noise” – basically, errors in where we think our body is – accounts for the wiggly path.

But some people are bad at navigating even by landmarks. Giuseppe Iaria and Jason Barton, are studying what happens in the brains of people who have a broken sense of direction. You can take their tests at the catchily named (which, um, I had trouble finding again after my first visit).

The series of tests takes about an hour, but it’s interesting to see what they think a sense of direction is made of. (They especially encourage people who have trouble navigating to take the tests.) The tasks include recognizing objects from different angles, recognizing faces (people with face blindness, called prosopagnosia, often have trouble navigating), recognizing landmarks after you’ve seen them in situ, and a variety of sleep-inducing walks through an almost featureless landscape, reminiscent of an empty Doom set, or a prison yard, where you’re asked whether you were led along two identical or different routes. In the most tedious test, the prison yard gets a couple of storefronts, and you’re asked to repeatedly locate them on a map. Despite my childhood difficulties, I did pretty well on the tests. It seems that landmark-based navigation works pretty well after all.