A Mind Of Her Own By Anne Campbell

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A Mind Of Her OwnBy Anne Campbell

• Annie Greynald
• Dana Stewart
• Keah Larsen

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Sexual, not natural selection

• animal that survives but doesnt reproduce leaves
  no genes behind
• sexual selection the advantages which certain
  individuals have over other individuals of the
  same sex and species, in exclusive relation to
  reproduction.
• genes enhancing good reproduction will flourish
  even if earlier death is result

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Sex differences derive from sexual rather than
natural selection

• genetic trait increasing the number of children
  reared will be passed on
• but the traits assisting these genes are
  different in men and women
• such genes may be activated by sex-specific
  hormones, thus men and women show different
  expressions of these genes.

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Anisogamy the start of parental inequity

• advantages of parthenogentic species
• 1. no time wasted looking for a mate
• 2. no exposure to predators while copulating
• 3. no concern of desirability
• 4. dont sacrifice 50 of genes
• advantages of sexual reproduction (mating)
• 1.unique individuals
• 2.less competition
• 3.increase odds some will survive environment
  with unique immune systems

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Why an egg and sperm?

• mutations and variability occurred in gamete
  size, some giving more or less than half of their
  chromosomal information
• those who gave less, produced more those who
  gave more, produced less
• sperm and egg
• large gametes good for egg because they must
  carry nourishment for growing zygote to survive
• small gametes good for sperm because they are
  small, cheep and mobile
• medium gametes had neither advantageonce
  anisogamy began, the gulf between only became
  larger

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Robert Trivers

• key reproductive difference between sexes
  parental investment
• r-k selected distinction holds for men and women
• minimum biological costs of reproduction are much
  greater for females
• 20 eggs/month vs. 300 million sperm/ejaculation
• by the time baby arrives, mother views offspring
  as huge emotional and physical investment

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Sex differences result from the females greater
biological investment compared to men

• psychological differences are side-effects
• men have plenty of time to desert female while
  she develops the ovum for 9 months
• desertion leads to future reproductive prospects
• women have no benefit from desertion of a male

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Why such a long period of parental care?

• 9 months is a compromised gestation period
• later than 9 months the head becomes to big to
  fit through pelvic bones
• earlier than 9 months, offspring would be too
  immature to survive

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However, babies are still born too early in a
maturational sense

• they are completely dependent on parental care
• women will provide more parental investment
  because infant represents huge biological
  investment

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Man and the attraction of polygny

• ideal condition for reproductive success is
  access to many fertile females
• evolution has fitted men for polygny to enhance
  reproductive output
• evidence for this derives from examining sex
  differences

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Why Men Invest at All

• Need for additional parental care
• Paternal certainty
• Behavior of females

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Need for Additional Parental Care

• How important is paternal care to the survival of
  the infant?
• Is it more beneficial in terms of reproductive
  success to invest?
• Evolutionary past show a high correlation between
  father abandonment and child mortality.

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Paternal Certainty

• The greater the doubt the less willing is the
  male to invest
• Internal fertilization and concealed ovulation
  make it harder for the male to make certain of
  paternity.
• mate guarding has evolved as a means to lessen
  this uncertainly

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Behavior of Females

• Rewarding Monogamy
• Females should encourage monogamy by practicing
  fidelity.
• Discouraging polygyny
• Females should make it difficult for men to take
  part in a polygynous mating system. They can do
  this by being less willing to have casual sex and
  by patronizing women who do so.

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Women as choosy investor

• Environmental Factors
• Quality of male mate
• More parental investment

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Environmental Factors

• Females must ensure that her body has a
  reasonable chance of sustaining the pregnancy
• Suppression or even loss of menstruation is very
  common in environments of poor resources and high
  stress
• Stress is relative
• Babies are more likely to be born during seasons
  when the climate is moderate and food supplies
  are plentiful.

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Picking the right mate

• Concealed ovulation
• Creates uncertainty about who the father is. This
  way the woman can fool each man into believing
  they are the father and so encourage them to
  supply recourses and defense. This will make for
  a more likelihood of infant survival.
• Encourages monogamy. The male must go through a
  period of courtship in order to ensure that she
  has not and is not copulating with other males.
• Evolved as an advantage for women

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Picking the right mate

• Favoring healthy and attractive males
• sperm wars
• Only the most successful sperm with the strongest
  army will win and therefore impregnate.
• Female orgasm
• Increases the likely hood of conception
• More likely to occur when the female has strong
  feelings about the male.

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More parental investment

• The decision to investment in a child must be
  made carefully
• There are many points at which a
  less-than-optimum pregnancy can be knowingly or
  consciously halted.

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More Parental Investment

• Only a very small percentage of fertilized eggs
  make it through the first trimester
• Low success of implanting
• Miscarriages
• Concord fallacy
• If an infant is not viable than a woman is better
  off abandoning it as early as possible.

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Abortion

• Voluntary abortion is high among young women ages
  20 of less.
• ¾ is 18-19 year-olds choose to terminate their
  pregnancy.
• Material, personal and intrapersonal resources
  also play a role in the decision to abort.
• The best predicator of abortion is whether the
  father is willing to commit himself to the mother
• In the United States 65 of pregnancy among
  unmarried woman were terminated compared to the
  10 among married women.

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Abortion

• Another factor is the woman's own psychological
  stability.
• In addition, these women have a more likelihood
  of miscarriages and are also more likely to give
  birth to infants with health problems.

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Infanticide

• Infanticide is a last resort for a woman who
  believes that the investment in the current
  infant is not worth continuing.
• Factors in deciding to commit infanticide include
  deformity of the infant at birth, absence of male
  support, and economic hardship
• Post-partum depression a psychological
  adaptation that reduces attachment and may thus
  open the way to infanticide.
• associated with inadequate emotional and material
  support from the father, family, and friends.

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Women As Heavy Investors

• The birth of an infant is only the beginning of
  the mothers duties, not the end.

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Orphaned Infants

• To ensure the survival of her offspring, a mother
  must defend and feed her infant(s) and herself.
• The disappearance or death of the mother
  dramatically shortens the life expectancy of an
  infant.
• When a mother initially disappears, the effects
  in the infant are observed immediately in the
  rise of stress activated cortisol levels.
• Long term disappearance of the mother most often
  causes a shortened life-span for the infant.
• Jane Goodall observed this in the infant primate
  Flint.
• A North-western German coastal region have
  records that prove this phenomenon in humans.

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The Importance of Lactation for Mother and Infant

• In a mother, breast feeding suppresses ovulation,
  thus causing a better spacing between children.
• In infants, breast milk provides about half a
  gram of anti-bodies a day.
• For both, it is a pleasurable experience because
  of the release of oxytocin in the mother which is
  passed on to the infant.

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The Bond Between Human Mother and Infant

• Within 48 hours of birth, mothers can distinguish
  the cry of their own infant.
• Human mothers are able to distinguish between a
  distress cry and a hunger cry from a baby.
• As early as 2 months, the infant is able to show
  a negative response to strangers.
• An evolutionary force is behind an infants fear
  of strange males instead of females.
• When upset, most children prefer their mother
  over their father to provide comfort.

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Child Care

• Even in this liberal era, mothers do most of the
  routine childcare.
• In households where both parents work, such as
  Israel and Sweden, mothers return home and carry
  out a majority of the duties.
• In traditional and non-traditional families,
  mothers proved to be more affectionate, soothing,
  disciplining, and vocal towards the infant.
• The amount of child-care and play between father
  and child depends on the relationship between
  father and mother.
• When Divorce occurs, the mother almost always
  takes on the child-care responsibilities.
• In no state do mothers abandon their children at
  the rate fathers do.

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Pursuing Half The Point

• The pre-occupation with mating studies and the
  neglect of parenting studies.

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Male and Female Roles

• Males devote their time to finding the right
  mate, females devote their time to raising the
  offspring to maturity.
• Parenting is critical to the survival of the
  offspring, perhaps more than finding the right
  mate, however a womans role is seen by many
  researchers as unproblematic.
• The excitement of the pursuit of a mate is
  perhaps why more research is devoted to mate
  selection over parenting.
• The excessive study of male-male competition only
  confuses the fact that males competed because
  they were much less important.
• A loss of females would be much more hazardous to
  the human population than the loss of males.

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Criticisms
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Questions?