All multicellular living things, plants and animals, have a
life cycle. The overwhelming number of
species have sexual reproduction. Some organisms are relatively short
lived. A fruit fly lives about 55 days.
Mice live about 2 years. Most organisms live about ten to twenty years. Humans
are long lived and they live 70-100 years depending on where we live with outliers
that reach 115 years. Galapagos tortoises live about 250 years. Plants do better than animals. Bristle cone pines live 4000 or more
years. Redwoods reach 3000 years. There are cheater species like Norway pines
that live at least 9000 years by sending out shoots from their roots to produce
clones. So the original tree might be
long dead but its genotype keeps going through this budding and cloning process
that supplements new offspring by the old fashioned way (fertilizing an ovule
with a pollen grain in a flower).
The rule of life is that two gametes (for us, a sperm and an
egg) unite to form a fertilized egg which forms an embryo which forms a newborn
which matures through childhood to become a young adult, then a middle aged
adult, and then a senescent adult who eventually dies. We know that as a life
cycle. Humans are unusual among animals in having greater mobility (they spread
around the world), an intelligence that aids their survival, and a culture that
they can transmit orally, or in more recent times, by writing.
In the past 100,000 years of Homo sapiens as a species, half of that time we lived in Africa.
About 50,000 years ago humans moved out of the Middle East and headed westward
into Europe and eastward into Siberia and what is mainland China and south east into
what is now Indian and southeast Asia.
By 30,000 years they populated Australia and moved into the Pacific
islands. By 15,000 years ago they crosses from Siberia into Alaska and moved
south and East to populate the Americas. They still hadn't written
anything. They still hadn't built any
cities. They left their stone tools
behind and occasional tools of bone and wood that lucked out and survived in
caves and other debris relatively dry and free from decomposing bacteria. By the time the first Americans were settling
into the west coast of North America, the first farms were being developed in
the middle east and Asia. The first domesticated
animals, especially cattle and sheep were being domesticated in the middle
east. The shift to agriculture led to unexpected
outcomes. It led to the birth of
cities. It led to the birth of written languages
to allow trade to be recorded. It led to the development of scripture or religious
writings about the gods they worshipped. It led to a rise in the world
populations and humans could now be counted in a few millions around the world.
That population size remained fairly stable with barely two
children surviving to reproductive maturity in each family that began
parenting. Births were numerous but survival was slim. Humans had not learned
how to preserve food for lean seasons and years of extreme cold or heat or
drought or floods. They had not
developed a system of waste disposal and hygiene to ward off infectious
diseases. Few reached old age. Most communities consisted of children and young adults. Imagine surviving today without sewage
disposal, without antibiotics, without public health programs, without
chlorination of water, without pasteurized milk, without immunizations against
infectious diseases, without surgery, and without medications for failing organ
systems.
The population of the world increased again as cities fused
into nations. The world population did
not hit one billion until the industrial revolution when machinery improved
farming, food processing allowed storage of foods, printed books on medicine and health informed physicians throughout Europe, and the rise of
universities doing research allowed scholars to flourish. Even then, until the 1870s the chances of a newborn
child living the first two years of its life, was only 50 percent. Mean life expectancy was about 45. Two things
happened in the last half of the nineteenth century that changed human
population. The first was the germ theory that Pasteur, Koch, and Lister
developed and promoted. The second was
the Public Health movement that Virchow initiated in Germany and exported to
the industrialized world. By the twentieth
century a remarkable shift was occurring.
Children were almost guaranteed they would live to reproductive maturity.
This in turn led to very large families of 5 or moiré children. It led, in 1913, to the birth control
movement through the efforts of Margaret Sanger. First the rich, then the
middle class adopted it. By the Great
Depression of the 1930s the poor were also limiting family size to about two
children.
In turn
this shifted the world population. In
1850 it looked like a pyramid with a base of lots of children and few old
people at the top. At the close of the 20th century it looked like a
stele (think of Cleopatra’s Needle in Central park in New York City). The number of children was barely more than
replacement of those dying of old age. That
in turn had unanticipated outcomes. The
elderly depended on their children to support them. This did not change until
the 20th century when programs like social Security were introduced. We pay taxes so that we will have a place live,
food to eat, and medical costs taken care of as we get old. Health care in the US was neglected until the
late 20th century when President Johnson got Medicare and Medicaid
passed in Congress. A more complete
coverage of the poor and unemployed in the US was introduced by President Obama
in this 21st century.
The trend
to a shrinking base of young people will continue world wide. It will lead to a world with more old people
than young people. In the US this will
lead to the election of Representatives and Senators who will represent the
interests of the old. I predict this
will happen about 2050. I also predict
that it will lead to a Department of Aging in the President’s cabinet. I predict that this cabinet office will lead
to more effective retirement investment. It will lead to a change in health care delivery
(salaried health workers instead of fee for service). It will lead to the creation of a Domestic
Peace Corps for and by the aged who will focus on the productive years of older
citizens. If the standard of the 20th
century was 65 at the time of retirement, today that means 25 more years of
life after retirement. How should one
live? What resources will there be for education,
volunteer service to the neglected aspects of society, volunteer service to cut
the costs of health, housing, infrastructure, and municipal; services. That is where the pooled ideas and talents in
a department of the Aging will be easily made known and many of them funded.
In
Biblical times 70 was the expected age of death for most people who survived
childhood. There was no retirement. In
1920 the expected age of death for most adults was 75 and retirement was about 65. In 2015 it is still 65 for retirement but death is
close to 90 in some industrialized nations. Most of us will have 15
good years of those 25 years of retirement. It is those last ten years where
the inevitable crumbling of our life cycle will take place. Given our penchant for discontent, what would
look like a fabulous blessing 200 years ago of human expectations will still be
seen by many as not enough. Whether we master the tools to extend life expectancy
farther, to slow down the aging process, or to fund our desires are beyond our capacities
to predict accurately. Fortunately, we
can address the problems of our own generation and let us hope we will do so.
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