Hi! Two quick remarks: First, there's some glitter on my face throughout this video. That's from my kid. I'm sorry. And secondly, just to be totally clear, this video is about giraffe mating. Okay, I think we can start.

Good morning, Hank it's Tuesday. So yesterday someone tweeted us. "You two do great work, have helped many, but sometimes I miss the days when you just made videos about giraffe sex." Fair enough.

So let's just recap the basics of giraffe sexuality. The majority of giraffe sex, according to one study up to 90%, occurs between two males. There's also occasional same-sex mounting between female giraffes, so heterosexual giraffe sex is not really the dominant form of giraffe sexuality. But it is how the babies get made. Now, giraffes can mate for procreation year round, but they tend to do it during the rainy season when food is less scarce because they're less stressed out and also because plentiful food makes the prospect of a giraffe pregnancy slightly less terrifying. 

So here's how it goes down. First, a male giraffe uses his head to poke a female giraffe in the butt. This sometimes causes the female giraffe to pee, as you can see here, and then the male giraffe will smell and/or taste that pee to determine if the female is fertile, which she is about four days out of every two weeks. If the pee tastes right and everybody is on board, the male will stand behind the female for a while until it is time for the magic to happen- the magic being a period of intercourse lasting less than two seconds. This extremely brief encounter is followed by more than a year of pregnancy. At the end of which, female giraffes usually produce a single calf, often born six feet tall and weighing over 150 pounds.

Needless to say, Hank, this is an inefficient process. I mean, first, you've gotta get a male giraffe to sexual maturity, which takes at least seven years. Then you gotta have enough food for the giraffes not to be stressed out. And then you gotta have the right-tasting kind of pee. And the you gotta be pregnant for 400 days. And then you usually just get one baby, albeit a gigantic and adorable baby. And even after that, your baby is very vulnerable to predators because it's so small and bad at running, but you can't, like, pick it up and put it in your pouch and hop away because you're not a marsupial!

All of this means that when giraffe populations go down, it's really hard for them to recover. And they are going down. In fact, a new report says that giraffe populations have fallen by around 40% since the 1980s. There are now only about 98,000 giraffes in the world, and they've just been moved to threatened status bu The International Union for the Conservation of Nature. The cause of the giraffe's decline is, of course, humans, mostly through habitat destruction and hunting. 

So it can be really hard to fathom just how thoroughly humans have reshaped the planet in the last few hundred years, but here's a bit of context. The total combined weight of living humans right now is around 300 million tons. The total combined weight of our livestock from sheep to chickens to cows is around 700 million tons. And the total combined weight of every non-human, non-domesticated large animal on earth, every penguin and elephant and shark, every whale and giraffe and lion, all of them combined, is less than 100 million tons. When geologists talk about the Anthropocene, the geologic age of humans radically reshaping the planet, that's part of what they're talking about. The earth's bacteria, by the way, have a combined biomass north of 350 billion tons, but I digress.

Right, so Hank, I think giraffes have a reasonably good chance of surviving the Anthropocene despite their inefficient mating. And that's not because their necks allow them to reach food other animals can't reach or because their kicks can literally kill a lion. It's because humans like them. We want them in the world, or at least I hope we do. And it really is our choice. If we lose the giraffe forever, there will only ever be one reason why: humans. Since the Colombian Exchange began a little over 500 years ago, thousands of species have gone extinct, and almost all of those extinctions are directly attributable to us. We decide. We are deciding right now what the biodiversity of our planet is going to look like, not for the next 100 or 1,000 years but for many millions of years. And maybe if we can accept that responsibility, we will begin to take it more seriously.

Hank, I'll see you on Friday.