The gang discusses two papers that look at the human impact on the fossil record. The first paper runs multiple model studies to try and determine when hominines (the group that includes all of our ancestors) first began significantly impacting the biosphere. The second paper estimates what our future fossil record may look like by using the state of Michigan as a model system (much to Amanda’s delight). Meanwhile, Amanda attempts to train a cat, Curt and James invent the best machine, James has his mind blown, and everyone wonders what the “prepper layer” of the Anthropocene will look like in a few million years.   Up-Goer Five (Curt Edition): Our friends talk about how people have changed the world. First, they talk about how big brains might have led to lost of animals dying. This first paper looks at how brains got larger in the great great great great parents of people over time. They run a lot of numbers in a computer in order to find out if the real big animals that died went away because of people or because of changes in the places where these animals live. They look at how big the brains of these people were, as well as how much rain fell and if there were trees. What they find is that, after running all the numbers, is that the best answer out of all the things they looked at was that these animals started to die when the brains of people got bigger. They think this could mean that the people with bigger brains started to take food from some of these big animals, and that made it harder for these big animals to stay living. The second paper looks at what we will leave behind after people are gone in the rocks. It uses a state that looks like a hand (and which one of our friends really really likes) as a way to look into this. Turns out, people cover things in ground a lot more than would usually happen without people. But people only cover in ground a small number of animals, like people, dogs, cats, and animals that we use on places where we make food. This means that the rocks after we are gone will look very different from the rocks before us. These rocks will be filled with just a few things, and most of those things will probably be in the same position. Also, a lot of the animals will all be men and all will have died for the same reasons.   References: Faurby, Søren, et al. "Brain expansion in early hominins predicts carnivore extinctions in East Africa." Ecology Letters. Plotnick, Roy E., and Karen A. Koy. "The Anthropocene Fossil Record of Terrestrial Mammals." Anthropocene (2019): 100233.