The effective altruism movement has three major focus areas: human welfare promotion, animal welfare promotion and far future catastrophic risk reduction (and a fourth, meta-level area of community building and priorities research). As I will explain, all these focus areas are important because there is a chain of interrelatedness. Working on one focus area can have negative side-effects. To counteract those negative side-effects, it is necessary to work on another focus area.
When we think about altruism, improving the well-being of currently living humans is the most well-known example. Helping humans is very tractable and is good according to almost all moral theories because we can be very confident that humans have a consciousness, humans can clearly express their needs and we have the means to make humans very happy. Especially people in extreme poverty can be helped in effective ways. Therefore, improving human health and economic development are the biggest parts of the first focus area of effective altruism. That is why most effective altruists support top charities recommended by GiveWell.
However, most humans consume animal products, and this consumption is positively correlated with economic development. For example: the diet of an average human in a developed country is responsible for the use and death of about twenty factory farm animals per year, and about one vertebrate animal per day (mostly bycatch and fish for fish meal).
The problem is: the production of animal products involves animal suffering. It is very likely that most farm animals have a negative well-being. Hence, saving the lives of humans or increasing their income levels increases animal suffering. This is the meat-eater problem of human development.
To counteract this negative side-effect of human development, we need to develop and promote plant-based, vegan or animal-free products from soy milk to clean meat. This is the first, biggest part of the second focus area of effective altruism: improving animal welfare. In other words, helping humans implies a duty to support effective animal charities, recommended by Animal Charity Evaluators.
However, vegan products have a lower ecological footprint than their animal alternatives. This means more land becomes available when we adopt vegan diets. Most humans value biodiversity for many reasons (such as instrumental value or esthetic value), so it is unlikely that this available land is turned into dead zones such as concrete deserts. It is more likely that these available land areas become natural ecosystems full of wildlife.
The problem is: it is very likely that there is a lot of suffering in nature, due to parasites, diseases, competition, predation, starvation and many other harms. It is even possible that a lot of lives of wild animals are not worth living, that those animals have a negative well-being. Hence, vegan diets might increase animal suffering in nature. This is the problem of wild animal suffering.
To counteract this negative side-effect of veganism, we need to promote scientific research how to intervene in nature to improve animal welfare. This is the second part of the second focus area of effective altruism. In other words, promoting veganism implies a duty to support organizations such as Wild-Animal Suffering Research that focuses on the well-being of wild animals.
However, it is possible that improving wild animal welfare involves using new technologies. There are a lot of wild animals, so it seems unlikely that humans will be able to fully improve animal welfare in nature. We might need assistance, most likely from artificial intelligence (AI), to monitor nature, to intervene in a safe and effective way and to calculate the possible consequences of interventions.
The problem is: developing safe AI is difficult. AI creates one of the most dangerous catastrophic risks. It is a very powerful technology that can easily be abused. And it is possible that AI-machines develop a superintelligence, that they become smarter than humans. This poses a catastrophic risk if the goals and values of these superintelligent machines are not aligned with the goals and values of organic sentient organisms such as humans and animals. This is the value alignment problem. As humans are the only hope for future wild animals, we have to make sure that humans do not go extinct by new technologies such as artificial superintelligence.
To counteract this negative side-effect of AI-development, improving the safety of AI becomes a priority. This is the biggest part of the third focus area of effective altruism: reducing catastrophic risks. In other words, promoting wild-animal suffering research and interventions implies a duty to support organizations such as the Machine Intelligence Research Institute and the Future of Humanity Institute.
Saving human lives also increases other catastrophic risks. More humans means higher emissions of greenhouse gases, increasing the risk of an extreme global warming. More humans means higher risks of pandemic infectious diseases, especially when those humans consume more animal products produced in factory farms that can create new zoonotic diseases. More humans means more intelligent brains that can create dangerous technologies. More humans means a stronger incentive to colonize other planets, terraforming those planets and hence increasing the risk of spreading wild animal suffering to other planets. These are all extra reasons why someone who helps humans has a duty to support work on the second and third focus areas of effective altruism.