DNA points to the cradle of humanity

Homo sapiens evolved in a vast wetland that once covered what is now northern Botswana, and stayed there for around 70,000 years before beginning our outward migrations. That’s the finding based on the mitochondrial DNA (mtDNA) of 200 people from rarely studied groups in southern Africa, including some who have the oldest mtDNA known in living people.

How evolution builds genes from scratch

In the past five years, researchers have found numerous signs of newly minted ‘de novo’ genes in every lineage they have surveyed. De novo genes are even prompting a rethink of some portions of evolutionary theory. Conventional wisdom was that new genes tended to arise when existing ones are accidentally duplicated, blended with others or broken up, but some researchers now think that de novo genes could be quite common: some studies suggest at least one-tenth of genes could be made in this way; others estimate that more genes could emerge de novo than from gene duplication. Their existence blurs the boundaries of what constitutes a gene, revealing that the starting material for some new genes is non-coding DNA (see ‘Birth of a gene’).

Four-thousand-year-old genomes show deep roots of social inequality

In a first-of-its-kind study, scientists have used ancient DNA to reconstruct the family trees of dozens of individuals who lived in a small German valley around 4,000 years ago. The genealogies point to social inequality within individual households, which encompassed both high-status family members and unrelated, low-status individuals — possibly servants or even slaves — as well as mysterious foreign females related to no one else.

Remains of 5,000-year-old 'cosmopolitan' city discovered in Israel

The remains of a large, 5,000-year-old city have been discovered in Israel. The early Bronze Age settlement covered 160 acres and was home to about 6,000 people.

Saturn moon count reaches 82

Twenty more moons have been discovered orbiting Saturn, giving the ringed planet 82 — at very least. The discovery establishes Saturn as the planet in our solar system with the most moons, surpassing Jupiter's 79. About 100 even tinier moons may be orbiting Saturn, still waiting to be found.

Lab-made primordial soup yields RNA bases

Organic chemists have created in the lab the nucleobases, adenine, uracil, cytosine and guanine — known as A, U, C and G — that could have served as the building blocks of RNA on an early Earth. The team put basic molecules through a series of conditions that could have existed way back when — cycling them from wet to dry, from hot to cold, and from acidic to basic, with chemicals occasionally flowing between two ponds. The results add credence to the idea that life arose from self-replicating, RNA-based genes before organisms developed the ability to store genetic information in the molecule’s close relative, DNA.

Giant exoplanet orbiting a dwarf star

Scientists are expressing surprise after discovering a solar system 30 light-years away from Earth that defies current understanding about planet formation, with a large Jupiter-like planet orbiting a diminutive star known as a red dwarf.

Stars are generally much bigger than even the largest planets that orbit them. But in this case, the star and the planet are not much different in size.

The star, called GJ 3512, is about 12 per cent the size of our sun, while the planet that orbits it has a mass of at least about half of Jupiter.