Ayala on the uniqueness of humankind & on the relationship between biology & ethics

1. Ayala on the uniqueness of humankind & on the relationship between biology & ethics • Francisco Ayala. “Human Nature: One Evolutionist’s View.” Whatever Happened to the Soul? Eds. Warren Brown, Nancey Murphy, & H. Newton Malony. Minneapolis: Fortress, 1998. • The specialness of humankind has biblical roots (Genesis 1:27). • Yet humans emerged in the evolutionary process from other animals. • Hominids emerged from chimpanzees 5 - 7 mya • Homo erectus - 1.8 mya Ayala on the uniqueness of humankind & on biology & ethics ~ page 1

2. Ayala on the uniqueness of humankind & on the relationship between biology & ethics • Homo neanderthalensis appeared in Europe ca. 200,000 tya ago and persisted until 30-40,000 tya. • Debate over the origin of modern humans • Multiregional hypopthesis • African replacement model Ayala on the uniqueness of humankind & on biology & ethics ~ page 2

3. Ayala on the uniqueness of humankind & on the relationship between biology & ethics • So what is distinctive about humans? • Anatomical traits • Bipedal gate & erect posture (we are only vertibrate species with these characteristics) (36). • Relative to body mass, humans have largest & most complex brain & reorganization of brain (cerebral cortex is much large than in other primates) Ayala on the uniqueness of humankind & on biology & ethics ~ page 3

4. Ayala on the uniqueness of humankind & on the relationship between biology & ethics • Opposing thumbs & arm and hand changes • Reduction of jaws & remodeling of face • Changes in skin & skin glands • Reduction in body hair • Cryptic ovulation & extended female sexual receptivity • Slow development • Modification of vocal tract & larynx Ayala on the uniqueness of humankind & on biology & ethics ~ page 4

5. Ayala on the uniqueness of humankind & on the relationship between biology & ethics • Distinctive human behavioral traits • Subtle expression of emotions • Intelligence: abstract thinking, categorizing, & reasoning • Symbolic & creative language • Self-awareness & death-awareness • Tool-making & technology • Science, literature & art • Ethics & religion Ayala on the uniqueness of humankind & on biology & ethics ~ page 5

6. Ayala on the uniqueness of humankind & on the relationship between biology & ethics • Social organization & cooperation (division of labor) • Legal codes & political institutions • Biological & cultural evolution • Are two kinds of inheritance • Biological -- endosomatic • Cultural -- exosomatic; makes possible the cumulative transmission of experience & knowledge from generation to generation Ayala on the uniqueness of humankind & on biology & ethics ~ page 6

7. Ayala on the uniqueness of humankind & on the relationship between biology & ethics • Cultural inheritance makes possible cultural evolution • Cultural inheritance includes a new modes of adaptation -- adaptation by changing the environment to suit the needs of our genes (39) • This adaptation, compared to biological, is much more rapid & can be directed Ayala on the uniqueness of humankind & on biology & ethics ~ page 7

8. Ayala on the uniqueness of humankind & on the relationship between biology & ethics • Biology & ethics • Evolution selected for human intelligence, not for ethics & ethical behavior • Human intelligence, in turn, has the capacity for ethics & ethical behavior • Thus the capacity for ethics is biologically determined, is part of human nature Ayala on the uniqueness of humankind & on biology & ethics ~ page 8

9. Ayala on the uniqueness of humankind & on the relationship between biology & ethics • But specific ethical norms are the product of cultural evolution • Ethical theories based on evolution tend to commit the naturalistic fallacy -- Herbert Spencer, E.O. Wilson Ayala on the uniqueness of humankind & on biology & ethics ~ page 9

10. Ayala on the uniqueness of humankind & on the relationship between biology & ethics Ayala on the uniqueness of humankind & on biology & ethics ~ page 10