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9.8 Option - The Human Story: 6. Current and future
trends
| Syllabus reference (October 2002 version) | ||
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6. Current and future trends in biological evolution
and cultural development
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Students learn to:
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Students:
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Extract from Biology Stage 6 Syllabus (Amended October
2002). © Board of Studies, NSW
Prior learning: Science Stages 4-5 syllabus: Outcome 4.8.3 (b), Outcome 5.8.2 (b) and (c),
Preliminary module 8.3 (subsections 7)
HSC module 9.3 (subsections 4 and 5)
Background: In the past, human evolution has been under the control of the environment. Now, and into the future, evolution will be more cultural than biological in nature.
gather, process, present and analyse information
from secondary sources to account for changes in human
population numbers in the last 10 000 years and to discuss the
potential impact of named examples of modern technologies on
future human populations
The information following draws on estimates of human
population growth produced from data identified from at least
three sources
Early humans lived for 1.5 million years in small groups. The numbers were kept low by predators and the availability of food. The table below records the growth of the human population.
| Years before present | Estimated human population (million) | Culture |
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10 000
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5
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early agriculture
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6 000
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7
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advanced agriculture
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150
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1260
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industrial revolution
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40
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3040
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technological revolution
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The factors that affect population growth are related to
birth and death rates. During the last hundred years there
has been a dramatic reduction in the death rate leading to a
population explosion. Reasons for this include increased food
supplies through agriculture advances, improved diet,
improved medical technology, the advent of sanitation and
public health programs, education and technological
advancements. Many humans would once have died at a young age
but are now living longer and dying of degenerative diseases
such as cancer and heart disease. Humans are no longer
selected for their favourable genes by the environment.
Instead humans change the environment to suit their own
needs.
- Gather information from a range of resources. You have to gather information to account for changes in human population numbers in the last 10 000 years as well as information to discuss the potential impact of named examples of modern technologies on future human populations. Consider these two points separately.
For the first part look at the table above and find
information on the population at other times in the last 10 000
years, say 4 000 years ago, 2 000 years ago and 1 000 years
ago. If you are using a search engine some words to search for
could be ‘human health’, ‘hygiene’,
‘estimated population’, ‘vaccination’,
agriculture, ‘education’,’ technology’.
The Internet sites below are a good starting point.
For the second part consider such new technologies as
‘cloning’, ‘genetic engineering’,
diagnostic medical machinery such as Magnetic Resonance Imaging
(MRI)
The Internet sites below are a good starting point.
Cloning 
How stuff works
Project
Future Shock, High
Technology and the Human Prospect Uncommon Knowledge, Hoover Institution,
Stanford University, California, USA
- Process the information by assessing the accuracy of the calculations and the relative importance of the data and information gathered.
- Present the information as a report.
- Analyse the information by making generalisations about the growth of the human population.
Useful information
Two named technologies that have had an impact on future
human populations are cloning and gene replacement technology
(gene therapy).
A clone is an exact genetic copy of DNA, tissues or an
organism. Plant cloning has been going on for a long time but
it has been harder to clone animals. There are two methods of
cloning animals, embryo splitting and nuclear transfer. In
embryo splitting, the embryo is split before it reaches the
32-cell size. This occurs naturally when identical twins are
formed. In nuclear transfer cloning the nucleus of one animal
is transferred to the cell of another organism (for example,
Dolly the sheep). Cloning tissues for organ transplants is
another use of cloning. Cloning skin for burn victims already
occurs but if it is possible to clone nerve cells and more
complex organs from stem cells then this will affect the
future evolution of humans. It has been discussed that it may
be possible to clone extinct animals such as the Thylacine
(Tasmanian tiger).
Genetic therapy is the insertion of a working gene into an
individual where the gene is not operating. This is being
researched for the treatment of cystic fibrosis and insulin
dependant diabetes.
process information
from secondary sources to outline the purpose of the Human
Genome Project and briefly discuss its implications.
Background information
The Human Genome Project (HGP) is a six billion dollar
international project involving scientists from all over the
world. The aim is to map the human genome sequence, identify
the 30 000 genes, store the information on a database,
develop tools for data analysis and address the ethical,
legal and social issues that may arise. The implications of
the project are both positive and negative. Positive
implications are that gene technology will reduce suffering
from disease, alert people to shortened life span because of
a predisposition to a genetic disease, and to produce useful
drugs and organ replacements through animal cloning. Negative
implications are that DNA could be used for social ranking,
biological weapons could be designed that are race specific,
parents could design children reducing the variation in the
gene pool, and insurance companies might refuse to cover
people because of their predisposition to genetic disease.
- Articles dealing with the Human Genome Project are appearing regularly in the mass media. Process the information by comparing the accuracy of scientific information provided by the mass media compared with the accuracy in scientific journals. The websites below are a starting point.
Beyond the Human Genome Poster and Presentation
Human Genome Project Information, Department of Energy, USA
Keeping Pace
with the Times - The Genetic Information Nondiscrimination Act of 2008
The New England Journal of Medicine
The Human Genome Project, Ethical, Legal and Social issues Department of Energy,
USA
analyse the possible effects on human evolution of the following
- increased population mobility
- modern medicine
- genetic engineering
Increased population mobility
- As human culture developed, humans became better at changing their environment. This led to an increase in population. Greater population resulted in greater pressure on the available resources and this led to increased migration.
- At the same time changing climatic conditions moved prey species and in response hominins followed their prey. Humans were in Africa and Eurasia 50 000 years ago. They entered Australia at least 50 000 years ago using boats and land bridges formed by the lowered sea levels as a result of the Ice Ages. Humans entered America across the Bering land bridge and then moved into South America. These isolated groups developed minor changes according to their environment, for example, people in cold climates tended to be shorter and stockier than people in hot climates who tended to be tall and thin. The short people maintained their body heat better and tall thin people were more likely to lose body heat and remain cool.
- With increasing technology better transport developed allowing faster transport between different human groups. The effect of this is that geographic barriers no longer exist as air travel means that no group is isolated from other groups. This allows gene flow between groups that would have previously been isolated and this should lead to breakdown in the concept of race. In fact genetic testing has shown that there is more variation within groups than there are differences between different ‘races’.
Modern medicine
- This is the result of the growing understanding of how the human body works and the diseases that affect it. Some examples of modern medicine are vaccinations, antiseptics, antibiotics, pre-natal diagnosis, in-vitro fertilisation and birth control. The effect of all of these is reduced mortality and increased life span. Childbirth is no longer responsible for the death of many women. Children survive because of vaccination programs.
- This changes the possible gene pool as fewer people are dying and are no longer selected by the environment. Diseases that once acted as selecting agents are not as relevant. Genetic defects can be passed on to the next generation because many sufferers live long enough to reproduce while before they would have died at an earlier age. These genes therefore stay in the gene pool and are not eliminated.
- Birth control is reducing the number of offspring from individuals so no longer are the ‘fittest’ organisms the ones that produce the most offspring.
Genetic engineering
- This is the manipulation of living organisms especially the manipulation of genes. This has had an effect in two ways. Firstly in the increase of agricultural production, supplying cheap food for more people and secondly through the changes to human survival rates. Modern agriculture produces high yields from crops and domestic animals. Examples of genetic engineering in agriculture include crops such as Round up ready cotton (herbicide resistant), cloning of crops such as carrots and Bt engineered crops that produce natural pesticides. The production of genetically modified crops (GM) has lead to arguments about whether these crops should be labelled.
- The changes to human survival rates have come through the control of genetic diseases. Genetic diseases such as haemophilia and phenylketonuria can now be controlled leading to a change in the frequency of these genes in the population. Genetic engineering can have vast effects on future evolution of humans. This ranges from an increase in food supplies from agricultural techniques through to direct interaction into the human genome.
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