Early pioneers thought cells from an embryo like the sea urchin would form only half a creature if separated (Image: Dr John Henson)
Read more: Instant Expert: Cloning
Artificial cloning of animals is one of the leading achievements of 20th-century biology, providing the means to create an organism that is an exact genetic copy of another – an identical twin. It is a far more complex business than the long-established techniques of cloning plants by taking a cutting such as a twig or stem and letting it take root – the origin of the term “clone”, from the Greek for twig.
There are now ways to clone all kinds of creatures so that the original animal and its clone share every scrap of DNA. Cloning has become a fundamental tool, with widespread uses in biology, from generating stem cells for medicine to breeding elite, genetically modified and endangered animals.
Nature’s clones
It’s not always appreciated that cloning is commonplace in nature, taking place in creatures as diverse as bacteria, vertebrates, and sometimes even in human beings too.
A few days after a mammalian egg has been fertilised by a sperm, the resulting embryo has to “hatch” from its rubbery covering, called the zona, so that it can implant in the wall of the uterus. Occasionally, the embryo will split and go on to develop into a pair of identical twins – each one a clone of the other.
This process of embryo fission was exploited in the earliest attempts to create an artificial clone.
Pioneers of twinning
The German philosopher and biologist Hans Driesch (1867-1941) was the first to create twins, back in…
![Astronomers have long known that understanding how star clusters come to be is key to unlocking other secrets of galactic evolution. Stars form in clusters, created when clouds of gas collapse under gravity. As more and more stars are born in a collapsing cloud, strong stellar winds, harsh ultraviolet radiation and the supernova explosions of massive stars eventually disperse the cloud, and their light can bear down on other star-forming regions in the galaxy. This process is called stellar feedback, and it means that most of the gas in a galaxy never gets used for star formation. Researching how star clusters develop can answer questions about star formation at a galactic scale. Now, the state of the art has been further developed with both Hubble and Webb working together to provide a broad-spectrum view of thousands of young star clusters. An international team of astronomers has pored over images of four nearby galaxies from the FEAST observing programme (#1783), trying to solve this mystery. Their results show that it is the most massive star clusters that clear away their gaseous shroud the fastest, and begin lighting their galaxy the earliest. The team identified nearly 9000 star clusters in the four galaxies in different evolutionary stages: young clusters just starting to emerge from their natal clouds of gas, clusters that had partially dispersed the gas (both from Webb images), and fully unobstructed clusters visible in optical light (found in Hubble images). With Webb???s ability to peer inside the gas clouds, they were able to then estimate the mass and age of each cluster from its light spectrum. This image shows a section of one of the spiral arms of Messier 51 (M51), one of the four galaxies studied in this work, as seen by Webb???s Near-Infrared Camera (NIRCam). The thick clumps of star-forming gas are shown here in red and orange, representing infrared light emitted by ionised gas, dust grains, and complex molecules such as polycyclic aromatic hydrocarbons (PAHs). Within these gas complexes, each tens or hundreds of light years across, Webb reveals the dense, extremely bright clusters of massive stars that have just recently formed. The countless stars strewn across the arm of the galaxy, many of which would be invisible to our eyes behind layers of dust, are also laid bare in infrared light. [Image description: A large, long portion of one of the spiral arms in galaxy M51. Red-orange, clumpy filaments of gas and dust that stretch in a chain from left to right comprise the arm. Shining cyan bubbles light up parts of the gas clouds from within, and gaps expose bright star clusters in these bubbles as glowing white dots. The whole image is dotted with small stars. A faint blue glow around the arm colours the otherwise dark background.]](https://images.newscientist.com/wp-content/uploads/2026/05/13114322/SEI_296271016.jpg)
