> From: michelle <mas396@soton.ac.uk>
> Date: Sun, 17 Nov 1996 18:35:38 GMT
> This is my additional theory to the question of sexual jealousy (I hope
> it's not a just so story) Male animals seem to be protective to there
> young until they are old enough to be able to "flee" from danger. At
> this point the Male knows that his genes will be passed on and
> therefore he is no longer needed and so disappears leaving the female
> to carry on rearing their young. This may prove to be disadvantageous
> to humans as rearing of young takes much longer and the female needs
> help for longer giving the child more chance of survival. So female
> humans want thier mates to be supportive.
I don't know whether it's true, statistically, that human males who
leave are more likely to do it when the young can walk; it seems to me
if they stay that long, they are more likely to stay.
> perhaps those genes that gave females the ability to show oestrus were
> in fact lost in the same way that humans have become less hairy!! I'm
> not really sure of the disadvantage as I haven't really looked deeply
> into my theory.
Actually, this is not an evolutionary explanation because you have not
tried to say what the adaptive advantage of concealed oestrus (or the
disadvantage of advertised oestrus) was, in terms of survival and/or
reproduction. Piggy-backing it on hairlessness is probably no help,
except if you have a joint story about the adaptive advantage of
hairlessness that is intertwined with the advantage of concealed
oestrus (or continuous advertisement of false oestrus, which is probably
a better description of what is the case).
As to why we evolved into the hairless ape: No one knows for sure but
there are plenty of theories, some based on temperature regulation:
(1) TI: LOSS OF BODY HAIR, BIPEDALITY AND THERMOREGULATION - COMMENTS
ON RECENT PAPERS IN THE JOURNAL OF HUMAN-EVOLUTION
AU: DOAMARAL_LQ
NA: UNIV SAO PAULO,INST PHYS,DEPT APPL PHYS,CP 66318,BR-05389970
SAO PAULO,BRAZIL
JN: JOURNAL OF HUMAN EVOLUTION, 1996, Vol.30, No.4, pp.357-366
KP: WATER BUDGETS, HOMINIDS, HEAT, ENVIRONMENTS, ADVANTAGES,
EXERCISE, ENERGY, BRAIN, FORM
(3) TI: PHYSIOLOGY, THERMOREGULATION AND BIPEDALISM
AU: CHAPLIN_G, JABLONSKI_NG, CABLE_NT
NA: UNIV WESTERN AUSTRALIA,DEPT ANAT & HUMAN BIOL,NEDLANDS,WA
6009,AUSTRALIA
UNIV WESTERN AUSTRALIA,CTR HUMAN BIOL,NEDLANDS,WA
6009,AUSTRALIA
LIVERPOOL JOHN MOORES UNIV,SCH HUMAN SCI,LIVERPOOL L3
3AF,MERSEYSIDE,ENGLAND
JN: JOURNAL OF HUMAN EVOLUTION, 1994, Vol.27, No.6, pp.497-510
AB: It has long been recognized that the bipedal posture reduces
the surface area of the body exposed to the sun. In recent
years, a theory has been developed by Wheeler that bipedalism
evolved in the ancestor of the Hominidae in order to help
relieve thermal stress on the animals in open equatorial
environments. Bipedalism was said to afford a distinct adaptive
advantage over quadrupedalism by permitting hominids to remain
active in the open throughout the day. The heat load of the
hypothetical hominid comprises the external environment as
modelled by Wheeler and the animal's internal environment
(i.e., the internal heat generated by its metabolic and
locomotor activities, and its evaporative and respirative
cooling capacities). When these factors are integrated in the
calculation of the animal's thermal budget, the putative
advantage of the bipedal over the quadrupedal posture is
considerably reduced. The simulations conducted in this study
suggest that the increased time afforded to early hominids in
the open by bipedalism was relatively short and, therefore, of
little or no adaptive significance. These results suggest that
thermoregulatory considerations cannot be implicated as a first
cause in the evolution of bipedalism in the hominid ancestor.
KP: FUNCTIONAL BODY HAIR, HOMINID BIPEDALISM, WATER BUDGETS, HEAT-
LOSS, ENERGY, BRAIN, ORIGIN, EVOLUTION, BALANCE, PATAS
WA: BIPEDALITY, THERMOREGULATION, ENERGETICS, THERMOPHYSIOLOGY,
METABOLISM, SWEATING, LOCOMOTION, FIELD METABOLIC RATE,
HOMINIDAE
(4) TI: THE THERMOREGULATORY ADVANTAGES OF HEAT-STORAGE AND SHADE-
SEEKING BEHAVIOR TO HOMINIDS FORAGING IN EQUATORIAL SAVANNA
ENVIRONMENTS
AU: WHEELER_PE
NA: LIVERPOOL JOHN MOORES UNIV,SCH BIOL & EARTH SCI,BYROM
ST,LIVERPOOL L3 3AF,ENGLAND
JN: JOURNAL OF HUMAN EVOLUTION, 1994, Vol.26, No.4, pp.339-350
KP: FUNCTIONAL BODY HAIR, WATER BUDGETS, BRAIN, BIPEDALITY,
EVOLUTION, BALANCE
WA: ACTIVITY PATTERNS, ENERGETICS, FORAGING, HEAT STORAGE, HOMINID,
NAKED SKIN, THERMOREGULATION, WATER CONSUMPTION
(5) TI: SWEAT AND THERMOREGULATION IN HOMINIDS - COMMENTS PROMPTED BY
THE PUBLICATIONS OF WHEELER,P.E. 1984-1993
AU: PORTER_AMW
JN: JOURNAL OF HUMAN EVOLUTION, 1993, Vol.25, No.5, pp.417-423
IS: 0047-2484
KP: FUNCTIONAL BODY HAIR, WATER BUDGETS, EVOLUTION, BIPEDALISM,
ENVIRONMENTS, DEHYDRATION, ADVANTAGES, GLANDS, SIZE
(6) TI: ORIGIN OF HABITUAL TERRESTRIAL BIPEDALISM IN THE ANCESTOR OF
THE HOMINIDAE
AU: JABLONSKI_NG, CHAPLIN_G
NA: UNIV WESTERN AUSTRALIA,DEPT ANAT & HUMAN BIOL,NEDLANDS,WA
6009,AUSTRALIA
UNIV WESTERN AUSTRALIA,CTR HUMAN BIOL,NEDLANDS,WA
6009,AUSTRALIA
JN: JOURNAL OF HUMAN EVOLUTION, 1993, Vol.24, No.4, pp.259-280
KP: FUNCTIONAL BODY HAIR, AUSTRALOPITHECUS-AFARENSIS, POSTURAL
BEHAVIOR, SEXUAL DIMORPHISM, PONGO-PYGMAEUS, FOSSIL SOILS,
EVOLUTION, ENERGY, CHIMPANZEE, LOCOMOTION
WA: BIPEDALISM, BIPEDAL DISPLAYS, HOMINIDAE, HOMINOIDEA, HOMINID
ORIGINS, HUMAN EVOLUTION, CHIMPANZEES
(8) TI: THE INFLUENCE OF STATURE AND BODY FORM ON HOMINID ENERGY AND
WATER BUDGETS - A COMPARISON OF AUSTRALOPITHECUS AND EARLY HOMO
PHYSIQUES
AU: WHEELER_PE
NA: LIVERPOOL JOHN MOORES UNIV,SCH ENGN & SCI,BYROM ST,LIVERPOOL L3
3AF,ENGLAND
JN: JOURNAL OF HUMAN EVOLUTION, 1993, Vol.24, No.1, pp.13-28
IS: 0047-2484
KP: EVOLUTION, SKELETON, RECONSTRUCTION, BIPEDALITY, AFARENSIS,
HAIR
WA: AUSTRALOPITHECUS, HOMINID, HOMO, PHYSIQUE, STATURE,
THERMOREGULATION, WATER, CONSUMPTION
(9) TI: THE THERMOREGULATORY ADVANTAGES OF LARGE BODY SIZE FOR HOMINIDS
FORAGING IN SAVANNA ENVIRONMENTS
AU: WHEELER_PE
NA: LIVERPOOL JOHN MOORES UNIV,BYROM ST,LIVERPOOL L3 3AF,ENGLAND
JN: JOURNAL OF HUMAN EVOLUTION, 1992, Vol.23, No.4, pp.351-362
IS: 0047-2484
KP: BIPEDALISM, EVOLUTION, BALANCE, ORIGIN, HAIR
WA: BODY SIZE, DEHYDRATION, ENERGETICS, FORAGING, HOMINID, SEXUAL
DIMORPHISM, THERMOREGULATION, WATER CONSUMPTION
(10) TI: THE EVOLUTION OF BIPEDALITY AND LOSS OF FUNCTIONAL BODY HAIR IN
HOMINIDS
AU: WHEELER_PE
NA: LIVERPOOL POLYTECH,DEPT BIOL,LIVERPOOL L3 5UX,ENGLAND
JN: JOURNAL OF HUMAN EVOLUTION, 1984, Vol.13, No.1, pp.91-98
(11) TI: ALLOMETRY OF PRIMATE HAIR DENSITY AND THE EVOLUTION OF HUMAN
HAIRLESSNESS
AU: SCHWARTZ_GG, ROSENBLUM_LA
NA: SUNY DOWNSTATE MED CTR,PRIMATE BEHAV LAB,BROOKLYN,NY,11203
JN: AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, 1981, Vol.55, No.1,
pp.9-12
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