Moral and economic trends will dramatically change the status of animals
Jan M. Brauner 18, PhD Candidate at University of Erlangen-Nuremburg, Freelance Researcher at the Center for Effective Altruism, BS in Physics from the University of Erlangen-Nuremburg, and Friederike M. Grosse-Holz, PhD in Plant Sciences from the University of Oxford, Master’s from The University of Freiburg, Master’s in Molecular and Cellular Biology of Plants from Heidelberg University, BS in Molecular Biotechnology from TU Munich, Consultant at the Boston Consulting Group, “The Expected Value of Extinction Risk Reduction is Positive”, Effective Altruism, 12/6/2018, https://www.effectivealtruism.org/articles/the-expected-value-of-extinction-risk-reduction-is-positive/
In today’s world, both farmed and wild animals outnumber humans by far. There are about 3-4 times more farmed land animals and about 13 times more farmed fish[6] than humans alive. Wild animals prevail over farmed animals, with about 10 times more wild birds than farmed birds and 100 times more wild mammals than farmed mammals alive at any point. Moving on to smaller wild animals, the numbers increase again, with 10 000 times more vertebrates than humans, and between 100 000 000 - 10 000 000 000 times more insects and spiders than humans[7].
In the future, the relative number of animals compared to humans will likely decrease considerably.
Farmed animals will not be alive if animal farming substantially decreases or stops, which seems more likely than not for both for moral and economical reasons. Humanity’s moral circle seems to have been expanding throughout history (Singer, 2011) and further expansion to animals may well lead us to stop farming animals.[8] Also financially, plant-based meat alternatives or lab-grown meat will likely develop to be more efficient than growing animals (Tuomisto and Teixeira de Mattos, 2011). However, none of these developments seems unequivocally destined to end factory-farming[9], and the historical track record shows that meat consumption per head has been growing for > 50 years[10]. Overall, it seems likely but not absolutely clear that the number of farmed animals relative to humans will be smaller in the future. For wild animals, we can extrapolate from a historical trend of decreasing wild animal populations. Even if wild animals were spread to other planets for terraforming, the animal / human ratio would likely be lower than today.