Adoption and altruism

It’s been a year since I first had symptoms of searing headaches, nausea and vision difficulties that lead to the detection of my brain tumor and subsequent surgeries to remove the tumor and to deal with complications from the tumor. What many don’t know is that this left me infertile.

My Ph.D. supervisor, GeneralSolutionGuru called the day after I found out, in part because we were working on a manuscript and I wasn’t able to deal with some of the revisions required immediately. She thought the brain tumor was back. When I told her, she was amazing. Compassionate, caring, and best of all - practical. GeneralSolutionGuru said that she was glad I was alive even if it meant trading off my fertility, but that she was so sorry I had to deal with the emotional fallout. We talked for a long time. And of course, one of the things that came up was adoption.

Adoption is a tricky business, especially for those who are not citizens of the country they are living and working in. As a Canadian, because neither my husband nor I have US citizenship or residency, we can’t start the adoption process – domestic or international. My preference is international, but it’s enormously expensive and frankly a single postdoc’s salary doesn’t cut it. If there are so many children needing a good home, why does it come at such a personal cost to the willing couple both in terms of time and money? It’s been said before but most fertile couples don’t have to pay a total cost of $40,000 just to get a child (at least that’s the cost internationally) – that cost comes later when the child is born, grows up, leaves the nest only to return home at the age of 30, and in some cases never to leave again.

HippieHusband and I are definitely considering it as an option, but it was this upfront cost led to me to ask the more evolutionary question, WTF? More explicitly, why do couples take on the care for another completely unrelated female’s offspring, especially when it costs so bloody much? In evolutionary biology, adoption is often cited as the primary example of altruism. This is because altruistic behaviour is defined, at least in the classical paper by Trivers (1971) as “behavior that benefits another organism, not closely related while being apparently detrimental to the organism performing the behavior.”

Another often cited example is – Is it altruistic to save a drowning man, at a cost to you? The traditional argument is only if the drowning man is completely unrelated to you in the genetic sense. Otherwise, it could simply be seen as a case of contributing to the survival of your own genes or kin selection. This is because saving the drowning man, who is genetically related to you, increases your inclusive fitness. Your genes get more copies in the next generation because you saved someone who has copies of your genes. This is famously called Hamilton’s Rule after a dude, who claimed he wouldn’t lay his life down to save a single brother, but would if it were for two brothers or eight cousins.

An alternative reason you might save the drowning man is that at some point there would be reciprocal altruism – maybe you weren’t drowning but your kid threw a rock at the drowning man’s bedroom window, it crashed through the window, and broke a very expensive Ming vase that he risked his life to get. But hey because you saved his life no harm done.

Although adoption is reported to occur in 62 different mammal species, many of these cases are among cooperatively breeding and/or highly social species where individuals within groups are genetically related. And really what international adoption, I think speaks to, is the highest level of cooperation amongst humans that are neither culturally nor genetically related.

In a paper published in PLoS One, Boesch et al. (2010) report 18 cases of adoption in a wild population of forest chimpanzees from Taï National Park, Côte d’Ivoire. These adoptions lasted in some cases for many years. The striking thing was that in captive chimpanzees cooperative behaviors are absent, but in wild populations of chimpanzees cooperative behaviors like food sharing, use of political coalitions, cooperative hunting and border patrolling are observed. These authors felt that the dichotomy between wild and captive suggested that socio-ecological factors may favor the evolution of altruism.

The authors defined adoption as any relationship between an adult and orphan infant where the adult shows species specific maternal behaviour to the child for at least two months. They also required that the adult be permanently associated with the orphan and exhibit behaviors like sharing food, providing protection during conflict, waiting during travel for the orphan. There was no obvious benefit to the adopting individuals while those chimpanzee orphans who were not adopted suffered huge costs in terms of survivorship. Those less than 5 years of age do not survive and many suffer delays in physical development. Surprisingly, the presence of close relative didn’t increase the likelihood of adoption. No gender biases were found in sex of the adopted orphan. It seemed like approximately equal numbers of males and female adults became foster parents.





One notable result was the extent and presence of parental investment in unrelated offspring by the chimpanzee males. In most polygynous primate communities, males typically do not invest much in their own offspring nor develop long term bonds with specific females. These male chimpanzees at Tai were not previously observed showing any obvious paternal behavior and yet they had adopted largely unrelated young.

Why then were these males exhibiting what the authors called altruistic behavior?

A major problem with this study was the non-estimate of the cost and benefit to the fostering chimpanzee. One suggestion the authors made about a possible long-term benefit was reciprocal altruism. Once the orphans became adults, they would become the allies of the foster males during conflict, however, males adopted both female and male orphans. But this could be extended to the case of food sharing, something the authors didn't mention. The fostering parent gets too old to forage and the adult orphan can now share the food they’ve obtained.

I imagine, however, that this scenario would easily invaded by cheaters. Adopted orphans that don’t reciprocate when it comes to conflict or food sharing.

Alternatively, Boesch et al (2010) suggested another benefit would be the improved social standing of the foster parent in the eyes of the group. This is a scenario that I think is likely to be at play in human societies. And I would imagine that in the group of chimpanzees that they followed it might be easily quantifiable. You could imagine that taking care of all members of the group in early human societies could benefit the persistence of that group.

In modern society, improved social standing may come something like this. One day you wake up and realize that you are the only one of all your friends who has yet to reproduce. People become friends with those who have similar interests. And if you are single or a couple without kids you are unlikely to have many friends who have kids and who will spend a great deal of time hanging out with you. Just take the bloggosphere. It is tremendously important to have women blog about managing career, personal life, and kids, but my connection and thus friendship with those female bloggers is limited, especially if they spend the majority of time blogging about their kids.

As I said the authors of the study didn't identify a fitness cost to the foster parents. Did the foster chimpanzees suffer reduced survivorship compared to those adults who didn’t adopt and did not have children of their own? Although I can’t put an estimate on my fitness cost, if I choose to adopt internationally, at least I know the dollar value on my upfront cost, the emotional cost, as well as my time investment away from work, and thus loss of income.

The authors suggested that because this population suffers from a high predation risk by a large population of leopards, within group solidarity in the form of care for all individuals will ultimately help the welfare of the group itself. While on the surface I feel that within group solidarity is part of if, to believe that socio-biological factors promote the evolution of altruism, these selective factors would have to be shown to be present in some significant form over many generations. From what I understand of population ecology, it is unlikely that the population of leopards would remain large and constant over time.

Finally, it was unclear whether this adoption event was a one hit wonder or if unrelated adoption actually occurs in multiple generations. Because we're talking about evolution, I'd like to know what happened in previous generations and if this practice will continue.

The authors have hit upon a really sexy topic, but their study was far from thorough. I know my own personal reasons for wanting to adopt, but this study left me highly unsatisfied as to why, from an evolutionary perspective, do humans invest so much time, money, and energy in international adoption?

Works Cited

Boesch et al. 2010. Altruism in forest chimpanzees: The case of adoption. PLoS One, vol.5(1):e8901

Trivers, R.L. 1971. The evolution of reciprocal altruism. Quarterly Review of Biology, vol.46:35-57.

Gorrell et al. 2010. Adopting kin enhances inclusive fitness in asocial red squirrels. Nature Communications, v22:1-4.