Anemia is a condition in which people lack enough healthy red blood cells to carry adequate oxygen to the body’s tissues. Anemia can often be caused by a lack of iron. In Survival of the…
read analysis of Anemia
Epigenetics
Epigenetics is a developing scientific field which suggests that certain compounds can attach themselves to specific genes and suppress their expression. For example, in agouti mice, feeding pregnant mice vitamins led the mice babies to…
read analysis of Epigenetics
Favism
Favism is an inherited disorder that affects 400 million people around the world. Favism results in a G6PD enzyme deficiency. The G6PD enzyme is designed to protect the integrity of red blood cells, including by…
read analysis of Favism
Folic acid
Folic acid is a B vitamin that is an integral part of cell growth. Folic acid helps DNA replication when cells divide, and thus it’s particularly important during pregnancy. Too little folic acid during this…
read analysis of Folic acid
Free radicals
Free radicals are molecules with unpaired electrons that can disrupt cellular chemistry. Such molecules can be found in fava beans, and when people with favism eat fava beans, the free radicals within wreak havoc on…
read analysis of Free radicals
Get the entire Survival of the Sickest LitChart as a printable PDF.
"My students can't get enough of your charts and their results have gone through the roof." -Graham S.
The Hayflick limit is the maximum number of times a cell can divide, because each time a cell reproduces it loses DNA. This limit was discovered by Leonard Hayflick in the 1960s, who found that…
read analysis of Hayflick limit
Hemochromatosis
Hemochromatosis is a condition that causes iron to build up in the body. Without treatment, it can lead to liver failure, heart failure, diabetes, arthritis, cancer, and ultimately death because of the damage it causes…
read analysis of Hemochromatosis
Transposons (“jumping genes”)
Transposons, or “jumping genes,” are sequences of DNA that can “copy and paste” or “cut and paste” itself into other parts of an organism’s DNA, thus changing the individual’s genome. Jumping genes were discovered by…
read analysis of Transposons (“jumping genes”)
Macrophage
Macrophages are a type of white blood cell which helps fight disease by finding and destroying pathogens. In people with hemochromatosis, macrophages have less iron than usual, which prevents pathogens from gaining access to…
read analysis of Macrophage
Malaria
Malaria is a disease common to tropical climates which infects almost 500 million people and kills more than one million people every year. Malaria is caused by parasitic protozoa which infect mosquitoes, and the disease…
read analysis of Malaria
Methylation
Methylation is the process by which genes are turned on or off by certain compounds without changing the genes themselves. Methylation is the key process that is studied in the field of epigenetics.
read analysis of Methylation
Retrovirus
A retrovirus is a virus made out of RNA which can copy itself into the DNA of an organism. Moalem posits that jumping genes are likely descended from retroviruses.
read analysis of Retrovirus
Phytoestrogens
Phytoestrogens are chemicals developed by plants which mimic the effects of sex hormones like estrogen and act as a defense against animals. When animals eat plants with phytoestrogens, they disrupt animals’ reproductive capability. Chemist Carl…
read analysis of Phytoestrogens
Weissman barrier
The Weissman barrier is the idea, put forth by August Weissman, that mutations in a person’s somatic cells (cells except for egg and sperm cells) would not be passed on to germ cells (egg…
read analysis of Weissman barrier
Younger Dryas
The Younger Dryas was Earth’s last ice age, which began around 12,000 years ago and lasted around 1,000 years. Its onset only took a decade. By that point, humans had started to migrate out of…
read analysis of Younger Dryas