I invite you for a walk in the park...

3. An animal is said to be altruist when its behavior
benefits other individuals, sometimes at a cost of
its own well-being.

4. Sebastião Salgado

9. Animal altruism is most obvious in kin
relationships, but may also be evident among
wider social groups.

14. In “The Selfish Gene”*, Richard Dawkins puts
forth three strategies of reciprocal altruism:
Suckers, Cheats and Grudgers.
*Chapter “You scratch my back, I’ll ride on yours”

19. Let’s say that a bird (B) has a parasite on the top
of his head and needs another bird (A) to remove
it. A pulls it off him.
A is a sucker and grooms others indiscriminately.

24. Later, A has a parasite on his head and seeks out
B in order that B may pay back his good deed. B
simply turns up his nose and walks off.
B is a cheat, an individual who accepts altruism
from others, but never returns it.

29. But now, suppose there is a third strategy
called Grudger. Grudgers groom strangers
and individuals who have previously
groomed them.
However, if any individual cheats
them, they remember the incident and
bear a grudge: they refuse to groom that
individual in the future.

30. *http://www.all-creatures.org/stories/a-love.html

31. A swallow is injured and the condition is fatal.
She was hit by a car as she swooped low across the road.

32. Her mate brought her food and attended to her
with love and compassion.

33. He came back with food again but found her dead.
He tried to move her... A rarely-seen effort for swallows!

34. Aware that she is dead and will never come back,
he cries out.

35. He stood beside her, crying out.

36. Finally aware that she will never return,
he stood beside her body with sadness and obvious sorrow.

37. Sebastião Salgado
IN MEMORY OF MY SISTER GLÓRIA
WITH LOVE AND COMPASSION