Laura Sahng

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The Crossing

Mandy Hager

Random House NZ


A group of people live on a remote island after the rest of the world’s population has wiped out. The people believe they were chosen by God to survive.

When the girls are old enough, they make the crossing to another island where they become a 'bleeder' or a 'breeder'. "Bleeders' are the people who are unable to give birth, so they are forced to give blood for the others until they die. This story is in the perspective of Marym who is to become a bleeder. This book has science about human ecology, about survival of the fittest and reduction in human diversity.

How does ‘survival of the fittest’ in the past affect our world today?

What does it mean if there is a reduction of diversity in humans?

What is survival of the fittest?
Survival of the fittest is a phrase that was made by two proponents Herbert Spencer and Charles Darwin.
The phrase means a natural process resulting in the evolution of organisms best adapted for its environment. So they may not be the strongest but the most cleverest or cooperative.

In 2010 two Dartmouth College biologists conducted an experiment with lizards. Ryan Calsbeek said, "... intense natural selection can also arise through competition. Sometimes, death by competitor can be more important than death by predator."
They found that increasing the number of lizards in an island caused them to compete for survival (food, space and resources) favouring the larger sized and the ones with a better running ability.

Without 'survival of the fittest', our world could still be roaming with dinosaurs. Every species that ever became extinct had not survived because it was not able to live in the conditions of the Earth. Over time, animals evolve so they better fit their environment. The experiment above shows that natural selection is an important part of adaptation and evolution. Without the competition within each species/animals, the weaker animals would be ill and animals could become endangered or extinct at a faster rate.

Evolution is a process which living things have developed and diversified from earlier forms during the history of the earth.

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Biodiversity is the result of 3.5 billion years of evolution!
There are still an estimated millions of plants, insects and other living organisms to be discovered.

In 2007, a study by the National Science Foundation found that genetic diversity and biodiversity are dependent upon each other. Diversity within a species is necessary to maintain diversity among species, and vice versa. Dr. Richard Lankau, the lead researcher in the study says, "If any one type is removed from the system, the cycle can break down, and the community becomes dominated by a single species."
Changes in biological diversity lead to changes in the environment, leading to adaptation of the remaining species. Changes in genetic diversity, such as in loss of species, leads to a loss of biological diversity.

Watch up to 1.40 (unless you would like to do the quiz!)

(Just a warning that at some time in this clip there are some nice close ups of frogs. So if you're like me you may want to watch the first Youtube video instead...)

The importance of biodiversity:
Not only in humans but in all living things it is important that there is diversity.
For animals, the food chain is something they rely on and it would effect the environment too.

There are some studies showing a loss of biodiversity linked to climate change.
There are many dangers that climate change brings like scarcity of fresh water and impacts of food resources.
Some of the health issues influenced by biodiversity include dietary health and nutrition, infectious diseases, social and psychological health.
Biodiversity is also known to have an important role in reducing disaster risk and in post-disaster relief and recovery efforts.
This could also affect business and economy.
Many industries rely on direct biological sources like oil, paper and food.
Biodiversity enriches leisure activities like tramping and fishing and inspires musicians, artists and many cultures believe and respect the natural world.
It is also important for the ecosystem services that are not visible like the chemistry in the atmosphere or water.

These last few centuries, scientist have been notices rapid decreases of biodiversity. They estimate that by 2050 up to 30% of all species will be extinct. One eigth of these that are threatened, are known plant species. Almost 140,00 species per year are expected to become extinct.
These figures show unsustainable ecological practices because only a few new species emerge each year.

Jared Diamond (An American scientist) describes an "Evil Quartet" of habitat destruction, overkill, introduced species, and secondary extinctions.

Biodiversity song!

Biodiversity Science is an online newsletter on updates about biodiversity developments and conservation research.!/biodiversitysci

University of Texas - Human Ecology!/UnivTexasSHE

How they relate to the book:

This relates to the book because the people that were not fit enough to give birth were killed and soon the people of Onewera will have wiped out all of those who were not able to live in the standards.

This is realistic because like Marym, there would be some other people like her who refuse to give blood and leave the island. They were made to be bleeders because they weren't fit to give birth so their genes would not be carried even if they lived their lives to the fullest. So in time, most people on Onewere would become breeders.

Onewere and the people of the island have survived a deadly event that destroyed the Earth and been 'chosen' to live.
There is no one else in the world they could meet so they wouldn't have a variety of cultures or nationalities.
This is realistic because if a group of people lived on the same island with similar genes, they would not be immune to foreign diseases or viruses that they may come across in the future.
This could potentially wipe out the population because none of these people have the genes that will protect them from other diseases.
In our world today, people travel to different countries and have ancestors from many different countries.
This helps us prevent sickness because our genes have received immunity towards some/more diseases.
Also, there wouldn't be a wide range of plant life on the island because only a few will pollinate and this may cause some problems in the natural processes.