1. Primate features Life history Brain size … after Lemuriformes Lemur catta

2. Brain Although the human brain is 3 to 4 times heavier than the chimpanzee brain, there is considerable similarity between the 2 species in convolutional details. Tattersall, Delson, van Couvering (1988) Encyclopedia of human evolution and prehistory.

3. Brain size Fleagle (1999) Primate Adaptation and Evolution

4. Neocortex Responsible for cognitive abilities Reasoning Consciousness In primates: 50-80% of the total brain’s volume ! Strier (2003) Primate Behavioral Ecology

5. Brain function Neocortex The brain is expensive: 2% of human body size 20% of energy required to maintain its activities ! ! ! Strier (2003) Primate Behavioral Ecology

6. Neocortex - Medulla Strier (2003) Primate Behavioral Ecology Neocortex Medulla Primitive part of the brain that controls basic body function such as respiration and heart rate. Insectivorous mammals:neocortex same size than medulla Prosimians: neocortex 10x larger Monkeys/Apes: neocortex 20-50x larger Humans: neocortex 105x larger

7. Log Brain Weight Log Body Weight C O G Measuring relative brain size 1.Brain Weight as a function of Body Weight 2.EQ= Encephalization Quotient = Observed / Expected brain size

8. Brain size Allometric relationship between brain and body weight for 309 extant placental mammals. Nest to humans? Dolphins! Primates have larger brain size ratio than the “mean mammal” Strier (2003) Primate Behavioral Ecology Mean for Mammals

9. Relative cranial capacity of macaques, gibbons, great apes and humans. Decreasing relative cranial capacity as body weight increases.

10. Iwaniuk et al 2001 JCP Correlates of larger brains : PLAY Larger-brained mammals play more than smaller-brained This is true between different Orders of mammals But not within the Orders of Primates or Rodents 15 mammalian orders

11. Reader & Laland 2002 Correlates of larger brains Executive Brain Ratio= (Neocortex + striatum) / (Brain stem)

12. Reader & Laland 2002 Correlates of larger brains 2. Social learning 1. Behavioral innovation 3. Tool-use Executive Brain Ratio= (Neocortex + striatum) / (Brain stem)

13. EBR and Innovation Positive relationship ! EBR and Social Learning Positive relationship ! Significant even when controlled for phylogeny Identical results between EBR and Tool-use Significant even when controlled for phylogeny

14. Members of large-brained primates innovate more often learn from others more often use tools more frequently than small-brained primates Reader & Laland 2002 Correlates of larger brains May have played critical roles in primate brain evolution Significance of the Executive Brain Ratio?

15. Prosimians have smallest neocortex ratios for their social group sizes Monkeys are intermediate Apes have the largest Social Brain Hypothesis (Robin Dunbar) Relationship between: size of neocortex size of social groups Strier (2003) Primate Behavioral Ecology

16. Within each of these grades: Primates with the largest grooming networks are those with the largest neocortex ratios ! ! Social Brain Hypothesis (Robin Dunbar) Strier (2003) Primate Behavioral Ecology The ability to maintain the social alliances was the PRIMARY selective factor in the evolution of large primate brains. Primates have social brains

17. Also in : Bats Carnivores Whales Social Brain Hypothesis Relationship between: size of neocortex size of social groups Reader and Laland (2002)

18. Deacon 1997 Ann Rev Anthropol Left figure: General pattern throughout life, showing brain growth slows down earlier than the rest of the body. Right figure: Prenatal general pattern, showing the same brain growth for all mammals surveyed. This demonstrates that the left-shifted primate growth is NOT the result of faster brain growth, but a reduced body growth. Developmental brain/body growth curves

19. Life History Fleagle (1999) Primate Adaptation and Evolution

20. Life History Fleagle (1999) Primate Adaptation and Evolution The most obvious correlate of life history variation is body size. Larger species: larger brain size ratio longer gestation fewer infants larger infants longer weaning ages delayed sexual maturity ? slower reproduction

21. Life History and BMR Strier (2003) Primate Behavioral Ecology Despite the large size differences between chimpanzees and gorillas, they have remarkably similar life histories. Among closely related primates, those with a higher BMRs and larger brains tend to take longer to mature and to be slower to reproduce.

22. Life History Strier (2003) Primate Behavioral Ecology Large-bodied primates need to eat more food than smaller primates. In absolute terms, their energetic requirements are greater. In relative terms, they need less energy per unit of body weight.

23. Fleagle (1999) Primate Adaptation and Evolution Delayed maturation in primates compared to other mammals. Furthermore in apes compared to primates. Further still in humans compared to apes

24. Life History Strier (2003) Primate Behavioral Ecology

25. Humans and primates: long period of slow childhood. growth accelerated at adolescence.Mammals: Growth curve decreases in rate from birth onward. Human growth curve compared to non-primate mammals Mammals Humans

26. Lemuriformes Madagascar: Single colonization event ~ 50 mya 5 families with > 60 species Humans arrived 1500 years ago on Madag. ONE-THIRD of all the lemurs disappeared ! ! Subfossils= large, slow moving, diurnal = easy prey, lots of meat ! !

27. Lemuriformes Diversity in social behavior Similarities with higher primates:  Convergence offers tests of socioecological principles Little sexual dimorphism in body size and weight In lemur species which lives in social groups  Females are dominant to males

28. Daubentoniidae 1 spp. – middle finger tracking insects – large brain-body ratio Cheirogaleidae – Dwarf lemurs Smallest primate = 30 g ! ! Megaladapidae (was Lepilemuridae) Sportive lemurs – nocturnal – adults lose their upper incisors ! Chromosomal evidence = 7 spp. Lemuridae 4 genera – most well known – high adaptability in zoos LEMURIFORMES Indriidae - Indrids 3 genera Unique locomotion Rowe 1996 Pictorial guide to the living primates

29. Eulemur fulvus albifrons Eulemur fulvus fulvus Eulemur fulvus rufus Eulemur = 6 spp. with different head color patterns Primary closed canopy forests Fruit, mature leaves, flowers, bark, sap, dirt, insects. Sexual maturity females = 10 months ! Rowe 1996 Pictorial guide to the living primates

30. Eulemur macaco Sexual dichromatism Sexual dichromatism: the condition in which males and females of a species differ in color. Primary & secondary Timber, plantations (cashew and coffee) Males aggressive during mating season One male observed to mate 6 times in 30 min... Female Male Rowe 1996 Pictorial guide to the living primates

31. Varecia variegata Ruffed lemur Intermembral index: 72 ! First to disappear (logging) Large fruits from large trees Pass seeds in 2-3 hours (good seed dispersers…) Rowe 1996 Pictorial guide to the living primates

32. Varecia variegata rubra Another subspecies Red form, black crown, white nape Rowe 1996 Pictorial guide to the living primates

33. Lepilemur ruficaudatus Deciduous dry forest Mostly leaves, also fruit Vagina closed, except mating season… Microcebus myoxinus Head & body length = 61 mm = 2.5 in. Testes increase in size when breeding season starts Rowe 1996 Pictorial guide to the living primates

34. Indriidae: Propithecus verreauxi Sifaka (after their barking call) Mating season = Jan to Mar. Females ovulate only once (!) Receptive for only 12-36 hrs (!) Females dominant over males (!) Males fight for dominance during the mating season only. Why? Because females mate with the alpha male only (!) Rowe 1996 Pictorial guide to the living primates

35. Photo by U. Thalmann. In Setchell and Curtis 2003. Field and laboratory methods in primatology. Cheirogaleus medius Nocturnal and arboreal Collar to track them Hibernation 7-9 months Body temperature drops from 33-38 C to 15 C Can lose up to 100 g (normal weight: 142-217 g) Hibernate in hollow tree trunk during dry season Solitary foraging but hibernate with 3-5 other members Feeds on chameleons (!) Data from Rowe 1996 Pictorial guide to the living primates

36. Lemur catta Ring-tailed lemur Dry-forest only 10,000 - 100,000 in wild ~ 1000 in zoos 3 - 3.5 kg

37. Diurnal, semi-terrestrial Multi-F, multi-M Female-philopatry Cavigelli 1999 Anim Behav Female hierarchy is linear Female dominance: nepotistic Male dispersal Like Female-Bonded Cercopithecines

38. Lemur catta Ringtail Cavigelli 1999 Anim Behav Promiscuous mating Stable groups (mean 18, multi-M) Frequent aggression Intergroup aggression, (both sexes fight) Wimmer & Kappeler 2002 Anim Behav Like FB cercopithecines

39. Wimmer 2002 Like FB Cercopithecines Higher-ranking males have high Rep. Success despite: brief mating season no sexual signals promiscuous mating

40. Cavigelli 1999 Anim Behav Like FB Cercopithecines Higher-ranking females produce more cortisol Sign of individual stress 1.Late gestation period 2.Feeding efforts were high 3.Anti-predation behaviors high

41. Wimmer 2002 Unlike FB Cercopithecines Fewer females (single matriline) Equal sex ratio among adults Brief synchronous mating season (2-4 days) (No prominent sexual signals) i.e. more intense male mating competition?

42. Unlike FB Cercopithecines No sexual dimorphism in size FF dominate MM completely No F-M friendships (contra Smuts’ study of F-M friendship among baboons)

43. Protect me !