Tag Archives: preferences

How Ancient Mating Preferences Shaped the Human Genome: Insights from Recent Study

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A groundbreaking study from the University of Pennsylvania reveals that prehistoric humans and Neanderthals interbred with a notable sexual bias, with male Neanderthals mating more often with female modern humans. This pattern may explain the scarcity of Neanderthal DNA in the human X chromosome and highlight the impact of social behaviors on our genetic lineage.

Prehistoric mating preferences help explain why modern humans carry small amounts of Neanderthal DNA in their genomes, particularly absent from the X chromosome. Image credit: Gemini AI.

“In addition to the X chromosome, there’s a significant gap in Neanderthal DNA referred to as the ‘Neanderthal desert’,” stated lead author Dr. Alexander Pratt, a researcher at the University of Pennsylvania.

“Historically, we believed these gaps resulted from certain Neanderthal genes being biologically harmful to humans, leading to their removal through natural selection,” he added.

New genomic analyses indicate that long-standing mating preferences, not genetic incompatibilities, influenced which Neanderthal DNA sequences were retained in modern human genomes.

This research illustrates how social interactions have shaped the human genome and challenges the notion that evolution is solely driven by the “survival of the fittest.”

“Our findings indicate a distinct sexual bias, with gene flow predominantly occurring from male Neanderthals to anatomically modern human females, which explains the limited presence of Neanderthal DNA on modern human X chromosomes,” remarked Dr. Platt.

“Approximately 600,000 years ago, anatomically modern humans and Neanderthals diverged, creating two separate evolutionary paths,” added Professor Sarah Tishkoff, the study’s senior author.

“While our ancestors evolved in Africa, Neanderthals adapted to life in Eurasia, yet this separation was not permanent.”

“Over millennia, human groups migrated into and out of Neanderthal territories, resulting in genetic exchanges during their encounters.”

To assess whether Neanderthal X chromosomes contained modern human alleles, researchers analyzed conserved DNA in three Neanderthal samples: Altai, Chagyrskaya, and Vindija.

They compared this data with that of a diverse genome from Africa, which hadn’t historically interacted with Neanderthals.

“Our analysis revealed a significant discrepancy,” noted co-author Dr. Daniel Harris from the University of Pennsylvania.

“While modern humans lack the Neanderthal X chromosome, the Neanderthal X chromosome contained 62% more modern human DNA compared to other chromosomes.”

This mirrored result indicates that if reproductive incompatibility existed, modern human DNA would also be absent in Neanderthal X chromosomes.

However, the presence of modern human DNA in Neanderthal X chromosomes rules out biological incompatibility as a barrier to reproduction.

The lingering explanation lies in the sexual bias in mating practices.

Given that women possess two X chromosomes and men only one, the direction of mating plays a crucial role.

If Neanderthal males mated more frequently with modern human females, fewer Neanderthal X chromosomes would integrate into the human gene pool, while more human X chromosomes would enter the Neanderthal population.

Mathematical models verified that this bias adequately explains the observed inheritance patterns.

While other factors such as gender-biased migration could lead to similar results, these scenarios are often complex and vary over time and geography.

“Our findings suggest that mating preferences offer the simplest explanation for these patterns,” concluded Dr. Platt.

For more details on this research, refer to the journal Science.

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Alexander Pratt et al. 2026. Interbreeding between Neanderthals and modern humans showed significant sexual bias. Science 391 (6788): 922-925; doi: 10.1126/science.aea6774

Source: www.sci.news

Ancient DNA Uncovers the Dietary Preferences of the Roman Empire

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Modern rendition of garum, a fermented fish sauce dating back to Roman times

Alexander Mychko / Alamy

Garum, a type of fermented fish sauce, was a favored condiment throughout the Roman Empire. Recent analyses of ancient DNA extracted from the production vats have uncovered the specific fish species used in this staple seasoning.

This Roman fish sauce was widely appreciated for its intense salty and umami flavors. However, philosopher Seneca famously remarked that one variant had a price “as audacious as that of rotten fish.” There were various types, including a liquid known as Garum or Liquamen, and a thicker paste called Allec. The preparation involved fermenting fish and plant materials, complicating the identification of the fish species used.

According to Paula Campos from the University of Porto, Portugal, “The small, fractured bones and the acidic conditions contribute significantly to the degradation of DNA.”

Campos and her team conducted DNA sequencing on bone samples dating back to the 3rd century AD, sourced from a Roman fish sauce production facility in northwestern Spain. They compared numerous overlapping DNA sequences against the complete fish genome, allowing them to confidently identify the species involved.

This analysis revealed that the remaining fish was predominantly European sardines, aligning with previous visual identifications at other Roman fish processing sites. Additional fish species such as herring, whiting, mackerel, and anchovy have also been identified in various garum production locales.

This finding indicates that “even degraded fish remains” can yield identifiable DNA, suggesting that “it could enhance our understanding of regional variations in the main ingredients of historical fish sauces and pastes,” noted Analisa Marzano, a colleague from the University of Bologna, Italy, who was not involved in the study.

The research shows a comparison of ancient and modern sardines, indicating less genetic mixing among sardine populations across different marine regions in ancient times. This knowledge “may help us gauge the impact of human-environment interactions over the centuries,” Marzano explained.

For future studies, Campos and her colleagues intend to analyze additional fish species from other Roman garum production sites. “We’re broadening our sampling to verify if the results are consistent throughout the Roman Empire,” she added.

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Source: www.newscientist.com

AI that predicts flavor preferences can advise brewers on improving beer taste

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Beer brewers produce a wide variety of flavors from just a handful of ingredients

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Artificial intelligence that can predict taste from beer's chemical composition could help create alcohol-free versions that taste exactly like regular beer.

Predicting flavor from a compound is difficult because complex interactions between ingredients and the psychology of taste can result in surprisingly different perceptions, even among people who have tasted the same thing.

To deal with this, kevin verstrapen Professors at the University of Leuven in Belgium have developed an AI model that can predict the flavor profile of beer based on its chemical composition and suggest ways to improve the flavor.

The model was trained on beer reviews by a panel of 16 expert tasters who scored each beer on 50 attributes, as well as 180,000 public ratings from online beer rating websites. The study compared these subjective descriptions with measurements of 226 compounds in 250 Belgian beers.

“Hundreds of these compounds are received by our nose and mouth, but mostly in the nose, and then processed in the brain to give us what we think of as flavor,” Verstrepen says. “The fact that we can actually predict this accurately using machine learning is pretty amazing.”

Verstrepen and his team used this model to predict how to improve the flavor of beer by adding mixtures of specific compounds, such as lactic acid and ethyl acetate. The resulting beer was given significantly higher ratings by a panel of trained tasters.

In another study, which has not yet been published, after making the changes suggested by the model, non-alcoholic beer became indistinguishable from regular beer, Verstrepen said.

The idea is that brewers should aim to implement AI recommendations by tweaking recipes, rather than simply adding flavors, he says. “Simply adding pure aroma compounds is not really acceptable in beer brewing. All you need is malt, hops, water, and yeast.”

“So I look at it as a tool, specifically to be used to make better non-alcoholic beer, but not to take away the art of crafting good beer in an artisanal way,” Versträpen said. To tell.

topic:

  • chemistry /
  • Eating and drinking

Source: www.newscientist.com