I’m finally back and recovered from my journeys. Now that Irene is gone, along with my jet lag, let’s get back to talking about sex! This week: zebra finch ladies aren’t so shallow, the sticky egg gets the sperm, the dangers of becoming a zygote, the dangers of being overweight and pregnant, and sex at a certain age.
- We hear a lot about animals (usually female animals) that choose their mates based on some superficial characteristic: pretty colors, a good singing voice, or funky dance moves. But new research from the University of Exeter has found that personality is also important…in zebra finches. Female zebra finches that are more adventurous prefer adventurous males, regardless of their appearance. Shy females, on the other hand, did not appear to have a preference either way. I wonder if males are as interested in their mate’s personality?
- Looks like sperm have a sweet tooth. Scientists have known for a while that there is something about the human egg that makes sperm stick to it, but what exactly the glue molecules were was a bit of a mystery. The main problem is one of size: human eggs are tiny, about the size of the period at the end of this sentence. So pulling them apart to find the glue was a challenge. Using new, ultra-sensitive techniques, researchers have found the identity of the exact sugar molecules that bind sperm to egg. Next up: figure out what the sugar-seeking molecules are on the sperm.
- The first hours after fertilization are scary ones for a zygote. According to new research, early embryos only narrowly avoid degenerating into chaos. The few cells in the early embryo must develop in sync with each other, otherwise they won’t be able to form a functional organism. Scientists always assumed that this synchrony happened by default, but as it turns out it’s the other way around. Early embryos have to have a stabilization program running in order to avoid their natural default of totally failing to develop. How does it do this? If you looked at my last post, you probably know that an oscillating calcium wave is set up in the embryo at fertilization. According to computer simulations based on the biology of a developing embryo, the calcium wave doubles as a time-keeper for cell growth and division during development.
- We all know that what a pregnant woman puts into her body can profoundly affect her unborn baby. Recent studies have also shown that, even before pregnancy, your lifestyle could affect your future children. Women who are overweight or obese tend to have children who also become overweight or obese. A new study looked at the relationship between mother’s BMI before pregnancy and the distribution of fat in their newborn babies. The unsettling result is that across the entire BMI spectrum,mothers with higher BMI had babies with more fat, especially in their livers. These babies may be set on a trajectory at birth for ill health later on in life. The moral of the story: take care of yourself, for the children!
- Finally, since I like to leave on a high note, a study about how having an active sex life can help people deal with aging. The study looked at women between the ages of 60 and 89, and found that, while the frequency of sex was much lower than for younger women, women who were happy with their sex lives tended to be happier about their lives overall. This study is just another reason I roll my eyes when I hear people say that sex is only for reproduction. That may be true for some species, but for humans (and bonobos, and dolphins…) sex plays other important roles in our lives. And it doesn’t stop doing that just because you’re past your prime.