Thomas Malthus

I feel that Thomas Malthus had one of the strongest positive influences over Darwin's development of his theory of natural selection. 

Malthus' theory on population was very simple. It was based on the assumption that the power of the population is much greater than the power of the Earth to provide subsistence for man. Basically, if man kept reproducing at their capable rate, there would come a point in time when there would not be enough resources to feed the people. Yes, there would be enough people to make food but not enough of the resources used to make the food. This would lead to a famine or other disasters. Malthus said that a population could only remain within its resource limitations by "positive and preventative checks." He claimed these positive checks to be things like war, disease and starvation. The preventative checks that could prevent overpopulation were things such as late marriage, celibacy and birth control. These positive checks raised death rates and the preventative checks lowered the birth rate. Malthus' theory on population made people realize that there was a point that would come when we would run out of resources if everyone and thing reproduce at their capacity.

• All organisms have the potential of reproducing exponentially. Two rabbits are roughly capable of producing approximately 200 rabbits in their lifetime. Imagine if all 200 baby bunnies had 200 hundred more baby bunnies… and so on… and so on… That is exponential growth that has the potential of having us up to our eyeballs in rabbits. But we aren’t up to our eyeballs in rabbits, are we? Why not? This question is the starting point of Darwin’s work.

Malthus taught us that positive and preventative checks were needed to keep us from overpopulation. In the speaking of bunnies, there would not be enough food for the bunnies to survive. The mothers clearly need enough food and shelter to be able to reproduce. At a point in time, the natural positive checks would start to play a part. The bunnies would starve and die. A disease from a deceased bunny could spread and cause further deaths. 

• Organisms with better access to resources will be more successful in their reproductive efforts. The rabbits with more food and water and shelter will reproduce more offspring than those rabbits with fewer of these resources.

Malthus used the idea of positive and preventative checks in his theory often. Organism's that had the access to food would not die from starvation. Ones that did not have as good of access could possibly die from starvation showing us a "positive check". People with the capability to obtain birth control, would not be reproducing, showing a preventative check. There are so many different examples to prove his theory. 

I personally do not think that Darwin could have developed his theory of natural selection without the influence of Thomas Malthus.  After Darwin read Malthus' work in 1838, he realized that when animals were in their struggle to survive, they would retain the favorable features that they had, that would help them adjust to their new environment and basically forget the other traits and features that they had. This is what the Theory of Natural selection was born from. I feel like without Darwin reading Malthus' work, I do not believe Darwin's theory would be quite the same.

The attitude of the church very much so affected Darwin and his publication of his book On the Origin of Species. At that point in time, it was a big deal to be questioning the church. The church was looked at as the highest form of belief. Darwin's work would have everyone questioning the church and it's teachings. It was a risky move for Darwin to even think about questioning or going against the church.