AMY1 Gene: Starch Digestion & Evolutionary Role

The Role of AMY1 Gene in Starch Digestion

• AMY1, the salivary amylase gene, assists in breaking down starch into sugars in the mouth.
• Modern humans carry multiple copies of AMY1 to produce amylase, which allows them to extract more calories from starchy foods.
• It has been a mystery when ancestors first acquired the copies of AMY1 and how they multiplied.

Disagreement on Gene Duplication Timing

• There are differing views on when the AMY1 gene first duplicated, as stated in The Nature and Science papers.
• Both papers do agree on the later evolution of the gene, showcasing the link between the rise of agriculture and an increase in AMY1 copies in specific populations.
• Research indicates the genes were prone to duplication.

Evidences Linking AMY1 Copies and Starchy Food Consumption

• In 2007, George Perry et al. discovered a correlation between populations consuming starchy foods and a higher number of AMY1 gene copies.
• Perry hypothesized that humans who began cultivating starchy crops like wheat and yams and had AMY1 were able to absorb more energy, leading to improved survival rates.

Technological Advancements Enabling New Discoveries

• Due to technology improvements, researchers can now sequence larger portions of DNA.
• It allows for multiple copies of genes to be found on a chromosome.
• Peter Sudmant et al. reported that humans worldwide can have up to 11 copies of AMY1 per chromosome, while Neanderthals and Denisovans had less copies.

Analysis of Ancient Genomes

• Sudmant et al. analyzed genomes from 519 ancient Eurasians from 12,000 years ago.
• They found that the number of AMY1 copies increased from four to more than seven around 5000 years ago.
• It happened because some people had at least one duplicated amylase gene.
• Researchers estimate the initial gene duplication occurred at least 279,000 years ago when humans were still in Africa.

Research Confirming the Link Between Agriculture and Gene Copies

• Omer Gokcumen et al. reported a similar increase in AMY1 copies among European farmers over the last 4000 years.
• The study confirmed its potential link to agriculture.
• AMY1 duplications were also found in Neanderthal and Denisovan genomes.
• Gokcumen's team indicated that the gene was first duplicated before modern humans split from their early ancestors, estimated around 800,000 years ago.

Understanding AMY1 Copy Mechanisms

• Gokcumen et al. explained how AMY1 copies replicate.
• After the three-copy version, or haplotype, was formed, gene copies on chromosomes could cross over and duplicate or delete copies.
• This could then cause a repeated replication.
• These mechanisms may explain other cases of gene copy number variation.

Explore the role of the AMY1 gene in starch digestion and its evolutionary implications. Discover how the gene assists in breaking down starch into sugars and how the rise of agriculture is connected to an increase in AMY1 copies. Different views on when the AMY1 gene first duplicated are also discussed.