A Revised Timescale for Human Evolution Based on Ancient Mitochondrial Genomes
Qiaomei Fu,Alissa Mittnik,Philip L.F. Johnson,Kirsten Bos,Martina Lari,Ruth Bollongino,Chengkai Sun,Liane Giemsch,Ralf Schmitz,Joachim Burger,Anna Maria Ronchitelli,Fabio Martini,Renata G. Cremonesi,Jiří Svoboda,Peter Bauer,David Caramelli,Sergi Castellano,David Reich,Svante Pääbo,Johannes Krause
Source - http://www.cell.com/current-biology/fulltext/S0960-9822(13)00257-1
Current Biology, Volume 23, Issue 7, 553-559
Highlights
- Human mutation rates are directly calculated using securely dated ancient human mtDNAs
- The study provides improved molecular estimates for human evolutionary events
- The last major gene flow event between Africans and non-Africans was calculated to 95 kya
Summary
Background
Recent analyses of de novo DNA mutations in modern humans have suggested a nuclear substitution rate that is approximately half that of previous estimates based on fossil calibration. This result has led to suggestions that major events in human evolution occurred far earlier than previously thought.
Results
Here, we use mitochondrial genome sequences from ten securely dated ancient modern humans spanning 40,000 years as calibration points for the mitochondrial clock, thus yielding a direct estimate of the mitochondrial substitution rate. Our clock yields mitochondrial divergence times that are in agreement with earlier estimates based on calibration points derived from either fossils or archaeological material. In particular, our results imply a separation of non-Africans from the most closely related sub-Saharan African mitochondrial DNAs (haplogroup L3) that occurred less than 62–95 kya.
Conclusions
Though single loci like mitochondrial DNA (mtDNA) can only provide biased estimates of population divergence times, they can provide valid upper bounds. Our results exclude most of the older dates for African and non-African population divergences recently suggested by de novo mutation rate estimates in the nuclear genome.
Figure 1 Calibration schemes for inferring the rate of molecular evolution.