Did sex with Neanderthals and denisovans shape our immune system?

Did sex with Neanderthals and denisovans shape our immune system?Group b8Rebecca Hollman, Colleen Adam, Chang-Gun An

1Evolutionary BackgroundTwo archaic human groups, Neanderthals and Denisovans- both migrated out of Africa ~400,000 years agoNeanderthals migrated northwestward into West Asia and EuropeDenisovans migrated northeastward into East AsiaAncestors of modern day humans migrated out of Africa ~65,000 years ago to both places and began interbreeding

RecombinationGenetic recombination is any change in the combination of alleles on a given chromosomeDNA recombination can produce 200 X 8262 = 1,652,400 different antigen-specific B-Cell and T-Cell receptorsDue to gene recombination, each B-Cell receptor, antibody and T-Cell receptor has a unique amino acid sequence- enabling it to bind a unique epitope on an antigen

HaplotypeA haplotype is a group of genes, inherited together by an organism from a single parentIt is a result of DNA recombinationContains for every sequence in the genotype, two haplotype sequences that are compatible with the genotype sequenceHaplotypes can be used to trace migrations in the human population since they are so unique (one passed on from the mother and one from the father)

HLA-A,-B,-CHLA (Human Leukocyte Antigen) helps against infectious diseasePlays a protective role in recognizing cancer cellsAn example of an HLA haplotype is HLA-B*73:01HLA genes are some of the most variable and adaptable genes in our genome, in part because the rapid evolution of viruses demands felixibility on the part of our immune system

How do we know HLA genes came from archaic humans?Genotype sequencing showed that up to 6% of archaic DNA is in the modern day human genomeWithin one class of HLA gene, the researchers estimate that Europeans owe half of their variants to interbreeding (Parham, 1)Because of interbreeding and have variability on the HLA gene, modern day humans have stronger immunity to diseases prominent in their geographic location

DiscussionModern day humans acquired HLA genes, which were dominant immune-related genes, and were more likely to survive local pathogens in Europe, Asia and Oceania For small migrating populations, interbreeding with archaic humans could restore HLA diversity after population bottleneck and also provide a rapid way to acquire new HLA variants already adapted to local pathogens- increasing survival and haplotype diversity

Conclusions and Take Home MessageIn summary, interbreeding between archaic humans and ancestors of modern day humans gave modern human populations more variable and favorable HLA genes- therefore increasing the strength of the modern day immune systemSo the reason youre not constantly sick is that your ancestors decided to get it on with different species

Works CitedParham, Peter. "The Shaping of Modern Human Immune Systems by Multiregional Admixture with Archaic Humans." The Shaping of Modern Human Immune Systems by Multiregional Admixture with Archaic Humans. Science Magazine, 25 Aug. 2011. Web. 19 Nov. 2012. .Young, Susan L. "Canoodling with Cavemen Gave Healthy Boost to Human Genome, Study Finds." Stanford School of Medicine. Stanford University Medical Center, 25 Aug. 2011. Web. 19 Nov. 2012. .McGrath, Matt. "Neanderthal Sex Boosted Immunity in Modern Humans." BBC News. BBC, 26 Aug. 2011. Web. 19 Nov. 2012. .