Have there ever been as many mammals as there are now?

Question

I apologize for the weird question, but based on a Google search it looks like this topic hasn't been discussed before. I'm hoping that enough information about population biology is stored in the fossil record to answer this question. Humans have wiped out a lot of animals in a very short time, but I realized that mammals might be doing very well. First off, humans are mammals, and there are 7.6 billion of us. That's quite a lot. I don't believe any other animal species of our body size has such a large population. Second, humans have pets. A lot of them. And they're almost all mammals. Everywhere we go we take our cats and dogs with us. Many of them become feral and multiply prolifically. Third, our livestock. With the growth of human civilization came the growth of meat consumption, which, naturally, meant a lot more cattle. I think I read somewhere that cattle are contributing more to global warming than cars, through burping. Lastly, and probably most importantly: rodents. Cats chased us everywhere because rats chased us everywhere. They thrived on the grain we grew and their population exploded to the point that they became a global pest, and possibly humanity's greatest enemy. So, my hypothesis is that there are more mammals now than ever before in the history of life. Not in terms of species diversity, but in terms of headcount. If this is true, it would be remarkable, since the rest of the Animal Kingdom is currently suffering through a mass extinction.

Answer 1

First of all, this is a great question. However, the fossil record is significantly incomplete and does not offer a true head count of mammals in every time period.

Secondly, it would be difficult to get an accurate account of every mammal living today. While the technology is available, the time and money needed for this project is not feasible. In addition, there is the ethical issue of is you were to individually count each mammal, this may have a negative affect on the animal.

Thirdly, there are more species that have more numbers than the human population. The issue is the carbon footprint by humans have been ever increasing since the Industrial Revolution.And unfortunately, our carbon footprint continues to grow.