Can being smart get you laid? Plenty of humans list intelligence among the things they're looking for in a mate, but smart people seem to end up single as much as anyone else. Biologists have sought evidence in animals, but the examples they've found have been indirect and open to question. Now, however, we learn that in at least one species, females prefer males who smart enough to solve problems.

Professor Carel ten Cate of Leiden University, Netherlands established the value of intelligence in the mating market by showing female budgerigars become more attracted to males when they see them solving difficult problems.

Cate put 17 female budgies in individual cages, with two males in neighboring cages. Each female would size up the males, and spend most of her time on the side of the cage close to whichever she preferred. The chosen male might have been feeling smug at this point, even if he couldn't get to his paramour through the bars, but Cate had a twist in store. He removed both males and taught the non-preferred one how to access food within a closed petri dish and a box. The box was a particular challenge, since it took three steps to open.

Both sets of males were then returned to the female-adjacent cages and given the containers. The trained males put what they had learned to use, while the untrained ones floundered. After watching this occur, Cate reported in Science, the females changed their minds. When the previously rejected males opened the containers, they got not only food, but a lot more female attention.

Previous studies have revealed a female preference in some species for males with larger brains, along with other characteristics that are probably indicative of intelligence. Nevertheless, all these cases have alternative explanations, with the females attracted to something else that happens to come as a package with smarts. By tricking the females into thinking the males they'd initially rejected were smarter, Cate got around that problem.

Nevertheless, Cate was keen to eliminate other interpretations. Perhaps the females hung out with the problem-solving males not because they wanted to mate with them, but because they wanted to learn their tricks. To test this, the experiment was repeated, but with all-female trios. Once again the middle bird strongly preferred one neighbor, but this didn't change when the other one showed off new-found problem-solving skills.

Cate interpreted this as indicating both heterosexuality in the test budgies, and that problem solving was viewed as sexy, rather than something to be valued in friends. If this is accepted, it is evidence for the theory dating back to Darwin that rising intelligence is in large part a product of needing to impress mates.