What Does Hunger Feel Like To Non-human Animals?

Recently, the great folks over at Gizmodo brought up an interesting subject in their Giz Asks series. Giz Asks is “a series where we ask experts hard questions about science, technology, and humanity’s future.” Needless to say, they come up with some really great discussion topics. On Monday, writer Sophie Weiner asked professionals one question: How do non-human animals experience hunger?

The answers she received were spectacular and bring to light the incredible adaptations species all over the world have made in order to survive. In the wild, regardless of where they live, many species go for very long periods without food. Hibernating bears will go months during the winter, many reptiles will go even longer on a regular basis and Weiner even notes the amazing olm – a cave-dwelling salamander that can live up to 10 years without any food.

Hibernation in black bears typically lasts 3-8 months.

So how do these animals do it? First, how are they capable of going such long periods without food and second, do they not experience the same hunger pangs that we do? Thanks to Giz Asks, we’re able to find out.

Chris Braun; Professor and Chair, Department of Psychology, Hunter College:

“A species’ physiology is totally adapted to its typical food intake. If its normal feeding cycle has long gaps (hibernation, mating period, migration, etc), then the physiological adaptations include big fat stores, lowered metabolism, breakdown and use of muscle, stuff like that. That’s all about calorie intake and energy use. Any species that has long gaps in feeding must have these kinds of physiological tricks.

But hunger is a different thing. From a behaviorist point of view, hunger is an abstract variable that expresses the likelihood that an animal will work for food. It can be shown to be changed by past experience, including time since last feeding and memory (we always get hungry just before the dinner bell). It is also influenced by internal metabolic processes, but only indirectly. This is probably based on sensors of blood chemistry and fat metabolism within the body and nervous system.

Our own experience of hunger is a feeling of discomfort that’s proportionate to that abstract measurable hunger, but includes an empty feeling in the stomach and a motivation to find food and eat it, plus a feeling of satisfaction (or more, “yay, chocolate!”) when you get the food. It’s lunch time, so I guess you know what that feels like. But you also know from experience that [hunger] isn’t strictly tied to food intake (unfortunately).

Natural selection should fine-tune the internal sense of hunger to the feeding rhythm of the species. I think the same way a human can become engrossed in a task to the point they skip a meal without noticing, a migrating bird doesn’t “think” about food. If you grab it mid migration season and set up an experiment where it could work for food (push a lever), I guess it would never try. From the outside, it doesn’t look hungry. From what we can guess or analogize for it’s internal perspective, I guess it’s just not part of their consciousness, they would not feel hunger pangs, anxiety over where is the next meal or any kind of craving for food, the same way you don’t even notice lunchtime passing when you’re deeply engrossed in some other motivation.”

Adult Burmese pythons eat only once or twice a month.

Brian Palestis; Professor, Department of Biological Sciences, Wagner College:

“I don’t know the answer to the specific question of how hunger feels [to animals], but you should consider differences between warm-blooded and cold-blooded animals (endotherms and ectotherms). A lot of the energy we get from food is used to keep up metabolism and produce heat. Small endotherms like songbirds need to eat very frequently. Animals like snakes that can go long periods without eating are ectotherms, so don’t need to eat nearly as often.”

Weiner got many more responses from psychiatrists, biologists and neuroscientists. You can read the full article here: How Do Non-human Animals Experience Hunger?

The average Arctic tern migration distance is 44,055 miles; they travel from Greenland/Iceland to Antarctica every year.

It’s always a great idea to get insight from professionals about our animal cousins, regardless of how closely or not we’re related. As animals ourselves, being able to better understand each species’ way of surviving can often help learn how we have, and can, adapt ourselves.