An update in very important whale/dolphin friendship news —

You guys! Remember yesterday, when we learned that dolphins and whales in Hawaii have twice been caught spontaneously playing together? Apparently, this gets better. Dolphins in a French aquarium seem to be "speaking" whale—making whale-sounding noises at night that mimic the actual whale noises they hear all day on the soundtrack to the aquarium dolphin show they perform in. These dolphins have never met real whales. But dolphins are known mimics and it seems that they're capable of practicing and improving on mimicked sounds hours after the sound has gone away. (Via Mindy Weisberger) — Maggie •

Barry White's sperm quality: Why are deep-voiced men attractive?

Maggie Koerth-Baker at 1:41 pm • •

Here's a fascinating study that shines a bright spotlight of nuance on some of those maybe-too-simplistic assumptions we make about evolution, physical characteristics, and reproductive fitness.

If you've paid any attention to reporting on the science of what humans find attractive and why, you won't be surprised to learn that studies consistently show that deeper voices are associated with stereotypically manly-man characteristics such as hairier bodies and taller height, that men with these voices and characteristics are judged as being more attractive, and that deep-voiced dudes seem to get more action from more ladies.

Based on all of that, you might be tempted to speculate that a deeper voice is an outward sign of how fertile and virile a dude is and that ladies have evolved to be attracted to that show of baby-making prowess. And that makes sense ...

Except that men with deep voices also seem to have lower-quality sperm. At the Anthropology in Practice blog, Krystal D'Costa explains:

These assessments aren’t entirely made up. There is evidence that secondary sexual traits can predict health and fertility of a partner. Brilliant colors and showy displays have long been natural indicators of potential sexual fitness. For example, deer with bigger, more complex antlers also have larger testes and more motile sperm. Lower frequency sounds have been linked to larger body size across all primate species

However, semen analysis reveals that men with deeper voices have lower scores on seven motility parameters (7)—even when the lifestyle and environmental factors are accounted for. While men with deeper voices may have more sexual partners, they seem less prepared to pass on their genes. Researchers believe the lower sperm quality reflects a trade-off that comes with having to compete for mates:

“Animals have finite resources to partition amongst reproductive activities, and the theoretical models of sperm expenditure assume a basic trade-off between male investment in attracting mates and in gaining fertilizations. Recent studies of non-human animals are providing empirical evidence for this basic life-history trade-off. A number of studies have also reported short-term declines in semen quality associated with social dominance."

Via DNLee

Octopus walks on land

Maggie Koerth-Baker at 11:18 am • •

Perhaps you've heard the tale of the octopus that broke out of its tank at the aquarium and walked across the room to break into another tank where it proceeded to eat other forms of sea life.

That story is kind of an urban legend. It's supposedly happened at every aquarium in the world, but can't be confirmed. And experts have told me that the hard floors in an aquarium would likely seriously damage the suction pads of any octopus that tried it.

But the basic idea—that an octopus could pop out of the water and move across dry ground&dmdash;is a very real thing. Here, an octopus at the Fitzgerald Marine Reserve in California hauls itself out of the water, and scoots awkwardly around on land for a little bit (while some apparently Minnesotan tourists gawk), before sliding back into the water. It's not the most graceful sort of travel. But it can be very handy. Octopuses do this in nature to escape predators, and also to find food of their own in tidal pools.

As an added bonus: Scientific American just started an all-octopuses, all-the-time blog called The Octopus Chronicles. Check it out!

Video Link

A dinosaur's teeth can be a map of its travels

Maggie Koerth-Baker at 8:45 am • •

Bones can tell you a lot about a creature, but there's much more they can't tell you. Bones are not behavior. We know what the skeletons of dinosaurs looked like. But there's a great deal about their appearance and behavior that we can only guess at.

Sometimes, though, bones can surprise you. Sometimes, they carry secrets locked inside. At Not Exactly Rocket Science, Ed Yong writes about a new study that's uncovered evidence about dinosaur behavior, using information stored in the dinosaurs' teeth. The paper suggests that the North American Camarasaurus had a seasonal migration.

Reptiles replace their teeth throughout their lives and the dinosaurs would have been no different. Whenever they drank, they incorporated oxygen atoms from the water into the enamel of their growing teeth. Different bodies of water contain different mixes of oxygen isotopes, and the dinosaurs’ enamel records a history of these blends. They were what they drank.

It’s easy enough to measure the levels of oxygen isotopes in dinosaur teeth, but you need something to compare that against. How could anyone possibly discern the levels of such isotopes in bodies of water that existed millions of years ago? Local rocks provide the answer. The oxygen also fuelled the growth of minerals like calcium carbonate (limestone), which preserve these ancient atoms just as dinosaur teeth do. If dinosaur enamel contains a different blend of oxygen to the surrounding carbonates, the place where the animal drank must be somewhere different from the place where it died.

Palaeontologists have used oxygen isotopes to infer all manner of dinosaur traits, from the fish-eating habits of spinosaurs to the hot body temperatures of sauropods to the chilly conditions endured by Chinese dinosaurs. These atoms have acted as menus and thermometers. Now, Fricke has turned them into maps.

When you drink, you are what you think —

"To put it very simply, the experiments show that when people think they are drinking alcohol, they behave according to their cultural beliefs about the behavioural effects of alcohol." — Anthropologist Kate Fox, writing for the BBC. (Via Ed Yong) — Maggie •

Teen driving restrictions don't have as big an impact as expected

Maggie Koerth-Baker at 7:39 am • •

My friend Jim captured this excellent moment in science reporting this morning. Thankfully, as I check Google News now, the headlines are drifting more towards the real story, which is fairly interesting. Turns out, deadly car accidents aren't so much a function of driver age as they are a function of driver experience.

Basically, over the past few decades, several states have placed stringent limits on teenage drivers—usually when they can drive, and who they can drive with. The idea was to separate first-time drivers from risky driving situations, and a lot of people assumed these measures were saving lives. Instead, we now know, the rules merely shifted when the deadly accidents happened. Some lives were saved. But, in general, the results were pretty much a wash.

The researchers found that states with the most restrictive graduated licensing programs — such as those that required supervised driving time as well as having night-driving restrictions and passenger limitations — saw a 26% reduction in the rate of fatal crashes involving 16-year-old drivers compared with states without any restrictions.

But the rate of fatal crashes among 18-year-old drivers in those states jumped 12% compared with the states without restrictions.

A similar trend was seen when comparing drivers in states with strong graduated licensing programs with those in states with weak programs: The rate of fatal crashes among 16-year-old drivers was 16% lower but was 10% higher among 18-year-old drivers.

Overall, since the first program was enacted in 1996, graduated programs were linked to 1,348 fewer fatal crashes involving 16-year-old drivers and 1,086 more fatal crashes involving 18-year-old drivers.

The speculative response: You can place restrictions on new drivers that limit their exposure to situations where mistakes are likely to happen. But, eventually, they'll have to navigate those situations on their own. And when they do, the mistakes creep back in. So maybe we need to look for a better way to mitigate the mistakes than simply instituting age-dependent restrictions. Personally, I wonder what the results would be if driving education included time to practice driving (either virtually or on a test course) with the distractions they're likely to encounter in real life. I know I learned how to drive and talk at the same time, and how to know when to shut everybody up, by experience. Maybe there's a way to do that in a safer environment.

High temperatures change parenting behavior in birds

Maggie Koerth-Baker at 5:38 am • •

So here's a statistic I'd never heard before: Between 1979 and 2003 years, more Americans died from heat exposure than from hurricanes, lightning, tornadoes, floods, and earthquakes combined.

Wow.

That comes from Jason Goldman, a scientist and science blogger, who has a post up today about how animals that thrive in extreme heat situations actually manage to do that. Specifically, he's writing about a recent paper that studied how harsh environments change the parenting behavior of desert birds. Apparently, the hotter the nest, the more the male bird is likely to be involved in incubating the eggs.

Biparental care, which is the care of offspring by both male and female parents, represents a classic example of the trade-off between cooperation and conflict in social behavior in the animal kingdom. If they cooperate, parents can work to improve the odds of the survival of their offspring. By withholding care, however, an individual can potentially survive longer and increase the odds of successful breeding later in life. Assuming that biparental care is even possible in a given species, mathematical models expect it to occur anytime the possibility of offspring survival is significantly greater than when cared for by a single parent. In particular, the harsh environment hypothesis predicts that parents should both contribute to the care of their young in environments susceptible to harsh weather conditions, where food is scarce, where there is intense competition for resources, if desiccation of eggs is a possibility, or in areas where the offspring are regularly preyed upon.

The Kentish plover provided Al-Rashidi with the opportunity to conduct a particularly clever experiment. These birds lay their eggs on the ground, which means that the eggs as well as both parents have direct exposure to the surrounding environment. Some nests are located under bushes, and are therefore naturally protected from direct sunlight, while others are out in the open. This provided an obvious way for Al-Rashidi to create two experimental groups – one in direct sunlight and a second in the shade. In general, males tend to sit on the nest during the cooler nighttime, while females tend to take the daytime shift. The problem is that the females risk overheating if they incubate the eggs all day. The harsh environment hypothesis, therefore, predicts that the warmest nests will not only show evidence of more biparental care but that the two parents will take turns more often throughout the day.

... As expected, males and females both spent more time sitting on the exposed nests than the covered ones over the whole day, and as predicted by the harsh environment hypothesis, there were more change-overs – that is, they took turns more often – during the hottest part of the day at the exposed nests.