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When you get “The Talk” as a kid and learn about the birds and the bees, the information you get doesn’t have a timestamp. Unlike lots of other animals, there’s no such thing as the “mating season” for humans: People can get together and make babies at any time of year.

And clearly, they do. From what we can tell, the reason humans don’t have a mating season has to do with why other animals do. And a lot of it might involve how we raise our young.

Plenty of animals — like horses, some types of birds, goats, sheep, and other critters — have mating seasons. Appropriately, they’re called seasonal breeders. The members of those species only go through certain hormonal cycles during a portion of the year.

They lead to females releasing eggs, often physical changes in males, and behavioral changes that promote sexual activity. This strategy evolved to make sure that, when offspring are born, they arrive during a time of year when the environment is friendlier and there’s food available. For example, many birds in the Arctic Circle start laying their eggs in May, so that the chicks are born in June and July, when prey is abundant.

The start and end of these seasons are triggered by changes in the environment. For example, animals’ biological clocks might note the days getting longer, which is a sign of the arrival of spring. And that might spur the physiological changes necessary for procreation.

The human reproductive cycle, on the other hand, isn’t tied to a yearly clock. Like many other primates, we’re called continuous breeders, and we’re capable of producing offspring during any season. Admittedly, people aren’t equally fertile every day.

Roughly every month, there’s a window where an egg is optimally positioned to be fertilized. But that still happens on predictable, 28-day intervals throughout the whole year. Regardless, the evolutionary reasons for this aren’t quite clear.

It may just be that the environmental risks to our offspring aren’t as significant. Humans and other primates devote a lot of energy to caring for new babies, so those babies aren’t left to find their own food, or out vulnerable to the elements. But it’s hard to know for sure if this is the right explanation.

Of course, even without a mating season, there are still times during the year when people are more likely to have kids. Birth rates in the United States, at least, are highest in the summer and fall, suggesting that people are having more sex and conceiving more babies during the winter. That might be because, at least in many regions, the cold drives people indoors where there’s not as much to do.

It could also be because of sperm viability. A 2013 study in the American Journal of Obstetrics and Gynecology found that, in more than 6000 samples, average sperm quality was highest during the winter, when the cells are less likely to be damaged by heat. But babies are still conceived during warmer months — and in warmer climates in general.

Still, if you live in the United States and your birthday is in August, you are definitely not alone. It’s just not because of a mating season. Thanks for watching this episode of SciShow which is a Complexly production!

Even if humans don’t have a mating season, there’s still a lot to learn about sex in general. And that’s where one of our sister channels, Sexplanations, comes in! You can check it out at youtube.com/sexplanations. [♪ OUTRO ].