What our ancestors’ genomes can tell us about modern health

What our ancestors’ genomes can tell us about modern health

Subject: Science and tech

Section: Biotech

Context:

• Researchers recently use sequences of ancestral DNA to understand genetic diseases that affected ancient humans and onto the medicines and tools that early human communities used.
• Ancient DNA (aDNA) studies along with cutting-edge genomic techniques can provide unprecedented insights into the genetic makeup(profile) of our ancestors by extraction and analysis of ancient skeletal remains’ DNA.
• Ancestral DNA studies provides information about the genetic diversity and population dynamics of ancient communities, their migration patterns, interactions, and adaptations to local environments and diseases confronted and how the afflictions shaped human evolution.
• Researchers can understand pathogens spreaded in the distant past and trace their origins and evolutionary trajectories.
• By reconstructing the genomes of lifeforms-emergence, spread, and adaptation of infectious diseases throughout human history can be traced.
• Such study enrich our knowledge of evolutionary history and have implications for modern healthcare.
• Teach about the diseases to which our genes have rendered us susceptible as well as how health
• disparities arose between different populations.

Examples:

Common genetic diseases are the result of chromosomal abnormalities i.e. chromosome number changes (extra copies or deletions of entire chromosomes)– resulting in different clinical syndrome .

Ex: Down’s syndrome is caused by an extra chromosome 21. Klinefelter’s syndrome due to an extra X chromosome.

Turner syndrome by the loss of one of the two X chromosomes in women.

Ancestral DNA and a disease’s history:

• Chromosomal karyotyping is a method to visualise the complete set of chromosomes in a cell, and is among the best techniques to diagnose such abnormalities.
• However, karyotyping requires live cells, a laborious method to culture and stain them.
• But due advances, scientist use whole-genome sequencing data from fragmented and/or degraded DNA to understand chromosomal abnormalities in a DNA as well.
• For example, Francis Crick Institute in London researchers published evidence of some of the earliest known instances of Turner syndrome, Kinefelter’s syndrome, and Down’s syndrome in aDNA dating from the Iron age in Britain.
• Similarly, a research group from Italy, Germany, and the U.S studied DNA isolated from 22 mummified individuals from a variety of geographical regions and time periods-17 samples from 3600 BC ancient Egypt and others of (1500-1900) AD from Bolivia, Peru, Switzerland, and Australia, an interesting analysis of genetic variants associated with atherosclerotic cardiovascular disease in modern humans and their link with ancient humans were carried out.
• In all, the scientists said they cardiovascular disease has been widespread in human populations for at least 5,000 years. Thus, established link between ancient and modern health.

Linking ancestral DNA to diets

• Insights into the lifestyles of ancient humans can also be gleaned from their genetic remains.
• Microbes from pitch of the birch tree (ancient humans extensively used birch pitch to repair stone tools and possibly fix arrowheads) reveal information about the oral health of the individuals who chewed it.
• DNA analysis of chewed pitch by scientists from Finland, Norway, Sweden, and Turkey identified sort of imbalance of microbial species observed in people with inflamed gums (periodontitis).
• Scientist also matched DNA with a number of plant and animal species, hinting at the ancient people’s diet.

What else can ancestral DNA reveal?

• Provide big clues about the creation and development of stone tools.
• Research: (In the 1930s, in a cave in Ranis, Germany – (around 50,000 years ago- when modern humans, neanderthals, and Denisovans coexisted) identified a number of ancient stone tools.)
• Archaeologists re-excavated the cave more recently and found several bones remains.
• Through high-throughput sequencing, DNA sequences unequivocally pointed in the direction of Homo sapiens.
• Also, by radiocarbon dating, the samples were found to be some 45,000 years old.