In many ways, birds are like humans. Or maybe humans are like birds. No, that’s not right. Maybe both are animals and, as distantly related animals, share some attributes.
For instance, the behavior of both male humans and male birds is influenced by testosterone levels. While male birds don’t have external testes (can you imagine flying with those? — running upright is bad enough!) they do have internal testosterone-producing gonads. And new research has found that male birds with intermediate blood levels tend to do better.
In Costs and Benefits of Testosterone in Birds we learn that having high enough testosterone is good for a male bird’s mating success and survival. Testosterone gives a guy bird the starch in its spine (not the technical language) to acquire and defend a territory as well as the sexual drive to find/attract mates and . . . mate with them.
But while “enough” is good, “even more” is not better. In fact, it’s worse. The experimenters found that of the birds with their levels experimentally manipulated, those with levels near the wild average did the best. Too high means too much risky behavior, which leads to health-endangering fights and predation, etc. Too little means poorer territory (which includes poorer access to food and less desirable/safe nesting sites)as well as poorer reproductive success.
In another bird study, scientists found Wild Birds Opt for Conventional Food Over Organic, Study Shows.
Lead researcher Dr Ailsa McKenzie:
“We showed that when given free choice, wild birds opt for the conventional food over the organic, and the most likely explanation is its higher protein content.”
It may simply be an unfounded stereotype, but many human males, and a fair share of females, too, seem to prefer a fat and protein laden steak dinner over high-vegetable-content alternatives. For dessert: a calorie-rich but nutrition-poor piece of pie. Why? It’s elemental: our evolutionary history placed a premium on what was then higher value foods: protein and calories. Green leafies — a belly full of that would give you the energy to last a day at best. And for building muscles salad alone gets a failing grade.
While animals — birds and humans and thousands of other types — live in a present environment, their body plans and functioning physiology was shaped years ago, in one past. How well do they fit their immediate environments? Only time will tell.
June 8th, 2010 at 9:37 am
Why not go the whole hog and say that all animals and plants are alike? It would be true after all. All life is for itself. In what way particular species are for themselves is none of our business really.
If animals are green or grey, large or small, largely gregarious or mostly solitary, shaped this way or that way… these things are incidentals, irrelevant to the concept or framework that defines or identifies life.
June 8th, 2010 at 10:51 am
John -
Let’s see . . . trapezoids are like upright rectangles. So why not go the whole hog and call them circles?
Please.
None of our business? How so?