THE VERY EARLIEST GALAXIES
In July 2017, astronomers from Arizona State University announced in The Astrophysical Journal that they had managed to detect the earliest galaxies, formed some 800 million years after the universe exploded into being. This is a remarkable achievement, because it was not until a period between about 300 million and 1 billion years after the Big Bang that the universe became transparent, in what is known as the re-ionisation event (caused by the radiation from the first stars and galaxies). Detection of any objects at such an early stage in the life of the universe is extremely difficult, likened to detecting bodies in thick fog. By using the Dark Energy Camera on the 4-metre Blanco Telescope at Cerro Tololo Inter-American Observatory in Chile, together with a sophisticated filter, the researchers were able to detect 23 young galaxies in that fog, and determine that they dated from just 800 million years after the Big Bang.
1,700 MILLION STARS
In April 2018, the European Space Agency (ESA) released the second catalogue of data obtained by the Gaia satellite – it is an immense trove of information. Gathered over 22 months, it includes the positions and distances of 1.3 billion stars, with the positions and brightness of 1.7 billion stars. It also obtained effective temperatures, radii and luminosity for 76 million stars, time-series observations of over 550,000 variable stars, information on half a million quasars and, nearer home, observations of about 14,000 minor planets (asteroids) in the Solar System.
VISITORS FROM AFAR
On 19 October 2017, the Pan-STARRS 1 telescope on Haleakala, Hawaii, discovered an object, initially thought to be a minor planet or comet and known as A/2017 U1. The object, subsequently named 1I/’Oumuamua (which approximately translates from Hawaiian as ‘a messenger from afar’), was found to be on a hyperbolic orbit, implying that it came from interstellar space. Although it had already swung around the Sun, and was escaping from the Solar System, it was the subject of intense observation and study. It was thought to be dense, consisting of rock or metals, and thus not a comet. It is dark red in colour, probably as a result of irradiation by cosmic rays during many millions of years in interstellar space. Initially believed to be elongated or cigar-shaped, subsequent analysis of its light-curve, published in Astrophysical Journal Letters in March 2018, suggests that it is pancake-shaped.
Also in March 2018, another team of astronomers stated that the object was almost certainly originally ejected from a binary-star system. Calculations suggested that the majority of objects ejected from stellar systems would be icy, and thus cometary in nature. Ejection of a rocky object is more likely to occur from a binary system. However, results published in June 2018 indicate that its observed motion as it passed through the Solar System is best accounted for by assuming that solar radiation irradiated an icy surface, releasing material and causing an acceleration. In this case ’Oumuamua was of cometary origin. As such it possibly formed in the outer region of another planetary system; it would probably have been easier for it to be ejected from such a location than if it had formed closer to its parent star. To eliminate the remote possibility that the object could be an alien artefact, data from the Murchison Widefield Array in Western Australia was examined to check ‘Oumuamua for any radio emissions; the negative result was reported in April 2018 in The Astrophysical Journal.
Studies suggest that many thousands (possibly even millions) of such objects may pass through the Solar System every year, but are normally undetected. In May 2018, a team from the Université Côte d’Azur in France and the Universidade Estadual Paulista in Brazil reported that the object 2015 BZ509, although a permanent member of the Solar System, probably had an interstellar origin. It has a retrograde orbit, in resonance with that of Jupiter. Calculations indicate that this orbit has been stable for thousands of millions of years, effectively since the formation of the Solar System. The retrograde orbit strongly suggests that it did not condense from the primordial solar nebula and thus originated in another stellar system.
DOES PLANET NINE EXIST?
The controversy over the existence of a distant planet (Planet Nine) in the Solar System has taken a new turn. In 2016, astronomers announced that analysis of the orbits of distant Solar-System objects suggested that a large planetary body existed far from the Sun and exerted its influence on the orbits of bodies in that region. Subsequently, this result was called into question over observational bias. In July 2017, researchers at the Complutense University of Madrid published in Monthly Notices of the Royal Astronomical Society their analysis of the orbits of extreme trans-Neptunian objects (ETNOs) with average distances of more than 150 astronomical units (AU) from the Sun (1 AU is roughly the distance from the Earth to the Sun, around 150 million kilometres). New analysis of the orbits revealed the location of the nodes of the orbits (where the orbits cross the main plane of the Solar System). If there were no perturbing body – that is, if there were no Planet Nine – the nodes would be uniformly distributed in space. However, the nodes and orbits of the 28 ETNOs examined, together with a further 24 ‘extreme centaurs’ – asteroids with extremely eccentric orbits – were found to cluster significantly, suggesting that there is indeed a major planetary body in the remote Solar System beyond Pluto (the largest TNO). Indications are that the body lies at a distance of between 300 and 400 AU.
A WATER-RICH LUNAR INTERIOR
A further twist to the problem of the origin of the Moon came with the publication in July 2017 in Nature Geoscience, by researchers led from Brown University in the United States, that satellite observations of the lunar surface showed that volcanic deposits contained large amounts of water. Although high water content of surface samples had been determined back in 2008, when observations by the Indian Chandrayaan-1 lunar orbiting satellite showed that water-rich volcanic deposits were widespread on the Moon’s surface, the implication is that because the lavas originated in the lunar mantle, the latter must also be water-rich.
The discovery has implications for the question of the Moon’s origin, because the generally favoured theory is that the Moon accreted from a ring of particles created around the Earth when a Mars-sized body (known as Theia) collided with the young Earth. Such a collision would have vaporised hydrogen, which would not survive to form water in Earth's orbit. With such a method of formation, any water present on the Moon would have to have been accreted from cometary or meteoritic material before the body had completely solidified.
BOTH PARTICLE AND ANTIPARTICLE
In July 2017, a team of physicists from the University of California and Stanford University announced in Science the discovery of a Majorana particle. This came after an 80-year search for the fermion, underway ever since Ettore Majorana’s 1937 prediction that a particle that is its own antiparticle should exist. This fermion – of the family that includes the proton, neutron, electron, neutrino and quark – has now been shown to exist. Majorana particles have the property of being their own antiparticles, and it is considered possible that neutrinos may be Majorana particles. Although this current discovery does not have a direct influence on studies of the neutrino, it is hoped that it may offer some insight into the processes at work.
A NEW NEUTRINO?
Details published in early June 2018 on the arXiv website and reported at a conference in Heidelberg by scientists working with the MiniBooNE detector at Fermilab near Chicago suggest that a proposed new variety of neutrino, the sterile neutrino, may have been detected. Three varieties (flavours) of neutrino (electron, muon and tau neutrinos) are already known. The results come from a 15-year run of the experiment, where muon neutrinos are generated and travel underground to the detector. On the way, the muon neutrinos oscillate and some were expected to appear as electron neutrinos. In the event, an excess of electron neutrinos was detected. This suggests that the existence of sterile neutrinos has influenced the production of electron neutrinos.
If confirmed, the existence of a sterile neutrino would be extremely significant, because it would represent physics beyond the accepted standard model of physics. Sterile neutrinos would interact rarely with known particles, but primarily interact with gravity. Their existence would have major implications for cosmology, and they have been suggested as the origin of dark matter. The expectation was that sterile neutrinos would be extremely heavy, but the results reported indicate a very low mass.
Unfortunately, the confidence level of the findings is 4.8 sigma, short of the 5.0 sigma normally taken as implying a definite discovery. When the results are combined with those from a much earlier experiment, the Liquid Scintillator Neutrino Detector, the confidence level reaches 6. However, results from other neutrino experiments, including the IceCube observatory in Antarctica, do not reveal any evidence for sterile neutrinos, so confirmation by other experiments is still required. The field of neutrino physics is in a complex state at present. One experiment, measuring electron neutrinos produced in nuclear reactors, finds fewer interactions than predicted, which may indicate the existence of more than one variety of sterile neutrino.
On 17 August 2017, the LIGO gravitational-wave detectors in the United States and the Virgo detector in Italy both observed an event – the first to be discovered by both systems. Unlike black-hole mergers, where only a gravitational-wave event is seen, the collision of two neutron stars produces signals throughout the electromagnetic spectrum, from radio waves to gamma-ray radiation. The event, the very first of what is known as ‘multi-messenger astronomy’, opens up a new realm of observational astronomy. About two seconds after the gravitational-wave event, both the ESA INTEGRAL and the NASA Fermi gamma-ray satellites detected a short gamma-ray burst from the same direction, finally confirming that neutron-star mergers are the source of these gamma-ray events.
In October 2017, a whole series of papers were published of observations of this event at various wavelengths and particularly in the visible region, where the event was about 1,000 times as bright as a normal nova eruption (causing such an event to be named a ‘kilonova’). The evolution of the visible light confirmed predictions of the way in which the heaviest elements are forged. Elements up to the atomic number of iron may be created in the cores of stars, particularly those that later explode as supernovae and scatter elements into space. Anything heavier than iron requires an environment where elements are bombarded by free neutrons. This is not found in supernova explosions, but the merger of neutron stars releases neutron-rich material. Visible-light observations of this event first exhibited the signature of light elements, like those seen in supernova explosions, but then showed a behaviour that can be explained only by the presence of the heaviest elements such as gold and platinum. This strongly suggests that such elements have been created in neutron-star mergers.
From the gravitational-wave observations of the event, known as GW170817 in lenticular galaxy NGC 4993, it has been deduced that two stars of about 1.48 and 1.26 solar masses merged. But the true nature of the object that resulted from the merger is equivocal. It has a mass of approximately 2.7 solar masses, meaning that this is either the most massive neutron star known, or the least massive black hole. In a study published in June 2018, a team led by David Pooley (Trinity University, Texas, and Eureka Scientific) used observations from the Chandra X-ray satellite to examine the evolution of X-ray radiation from the event. The X-ray emission grew as the shockwave expanded over the first 100 days after the merger. However the level of radiation was not as great as expected if the remnant were a neutron star, which would itself contribute X-rays in addition to those from the shock. The conclusion is that the remnant is actually a black hole. A definitive answer should be obtained by continuing observations for at least another year. After that time, if the central object were a neutron star, its emission would overtake the radiation from the shockwave and there would be a major brightening in X-rays.
In July 2017 it was announced that major work was underway on the Kamioka Gravitational-wave Detector (KAGRA) on the west coast of Japan. This is the site of the Super-Kamioka neutrino detector; the gravitation-wave detector is being built underground. It is expected that work will be completed by the end of 2018.
EXOPLANETS AND A POSSIBLE ‘EXOMOON’
On 18 April 2018, NASA successfully launched the Transiting Exoplanet Survey Satellite which, unlike the previous Kepler mission, is designed to survey the whole sky. It will replace the ailing Kepler satellite, which examined some 150,000 distant stars, and instead survey about 200,000 relatively nearby stars. The satellite is in a lunar-resonant orbit, orbiting the Earth in 13.7 days (half the Moon’s orbital period).
In August 2017, a team of astronomers from Columbia University, working in the Hunt for Exomoons with Kepler collaboration, announced that they had probably discovered the existence of an ‘exomoon’ – a satellite of an exoplanet – from an analysis of data returned by the Kepler spaceprobe, which detected three transits of the body across its parent star, which lies at a distance of 4,000 light years from us. The exomoon appears to be very large, comparable with the planet Neptune in the Solar System, and to orbit a planet (known as Kepler-1625b) that is approximately the size of Jupiter, but has 10 times its mass.
TRULY NEW HORIZONS
In June 2018, NASA announced that the New Horizons spaceprobe (which flew past Pluto and was subsequently placed in hibernation mode) was ‘awake’ and preparing to pass the Trans-Neptunian Object (486958) 2014 MU69, now known by the unofficial name of Ultima Thule, on 1 January 2019. Little is known about this object, which is believed to be about 30km across; it is red in colour and very irregular in shape. It may actually be two bodies in contact, in what is known as a contact-binary asteroid. At the time of the encounter, the asteroid will be at a distance of 43.4 AU from the Sun and thus the most distant object visited by a spaceprobe.
ANOTHER MISSION TO MARS
On 5 May 2018, NASA also launched the InSight mission. Scheduled to arrive at Mars on 26 November 2018, the spacecraft will land and deploy a seismometer, together with a ‘mole’, designed to penetrate to a depth of 5m. In addition to detecting seismic activity (and thus information about the interior of Mars), it will take heat-flow measurements and use additional instrumentation to determine the exact rotation period and orientation of the rotational axis of Mars.
ASTEROID RETURN MISSIONS
On 27 June 2018, the Japanese probe Hayabusa2 reached its destination, the asteroid 162173 Ryugu. This is a C-type asteroid, consisting of carbonaceous material, and thus considered to be the oldest and most primordial type of asteroid, dating back to the formation of the Solar System. The ambitious mission is expected to spend about 18 months orbiting the asteroid, during which time it will deploy several small landers, including the German-built Mobile Asteroid Surface Scout. The plan is to drive an impactor into the surface to create a crater, from which previously sub-surface material will be sampled. The spacecraft will leave Ryugu in December 2019 and return to Earth with the asteroid sample in 2020. A NASA probe, OSIRIS-REx, is expected to reach the asteroid 101955 Bennu (another C-type asteroid) in 2018 August. It is also a sample-return mission, albeit with a different method of sample collection.
In June 2018 it was announced that the Cassini spaceprobe, which was deliberately steered into the cloud-tops of Saturn on 15 September 2017 at the end of its life, had detected complex organic molecules in the material ejected from the ‘tiger stripes’ near the south pole of the planet’s satellite Enceladus. Such compounds have previously been found only on Earth and in a few meteorites. Those detected are thought to have originated in reactions between water and hot rocks at the base of the satellite’s sub-surface ocean. Although not a sign of the existence of life on the satellite, they indicate that the body could support living organisms.
On 18 December 2017, scientists from UCLA and the University of Wisconsin–Madison announced that extremely ancient organisms had been identified in rocks from Western Australia with an age of 3,465 million years. The various microorganisms exhibited different characteristics: two employed a primitive form of photosynthesis; one produced methane gas; and two others consumed methane and used the products to create cell walls. The existence of such diverse activity at such an early stage in the Earth’s history, when taken in conjunction with the growing understanding of the prevalence of exoplanets in other systems, suggests that life is common in the universe, because it is exceptionally unlikely that diverse life should form so quickly on Earth, but not arise elsewhere.
EARLY CONTINENTAL CRUST
In April 2018, researchers from the Department of Geophysical Sciences at the University of Chicago announced that investigations of the strontium content of zircon crystals in rocks from northern Canada indicated that continental crust formed hundreds of millions of years earlier than previously thought. The research placed the age of the rocks just 350 million years after the formation of the Solar System. This is contrary to the previously prevailing view that the Earth was hot, dry and unlikely to harbour any life-forms for some 500 million years after its formation, but agrees with the results obtained from early rocks found in Western Australia. The investigation used a new, and so far unique, instrument known as the Chicago Instrument for Laser Ionization, with which they were able to count individual strontium-atom isotopes within the samples.
GREAT PERMIAN EXTINCTION
For many years there has been considerable discussion of the cause (or causes) of the Great Permian Extinction, which occurred approximately 250 million years ago and was the most severe extinction event in Earth’s history. About 95 per cent of marine and some 70 per cent of terrestrial life-forms became extinct. In October 2017, a team of scientists from New York University announced in Scientific Reports that they had obtained evidence that the event was caused by massive volcanism, most probably the extensive eruptions in Siberia that took place at that time. Using an inductively coupled plasma mass spectrometer to measure the abundance of elements at an atomic level, the researchers determined that anomalous amounts of nickel were present in a wide range of samples from various regions. The conclusion was that nickel-rich lavas were erupted by the volcanism that created the large igneous province known as the Siberian Traps. It was suggested that the magma interacted with existing widespread coal deposits to release large quantities of carbon dioxide and methane, causing the extreme global warming that occurred at the same time on both land and at sea. The circulation of the oceans became sluggish and they were also depleted in oxygen, leading to the mass extinction of marine life.
In July 2017, a team of scientists from Vienna University of Technology and Würzburg University announced in Nature Communications that their research indicated that rather than the Earth’s magnetic field being created by the motion of molten iron, it was essential for a large percentage of the molten interior to consist of nickel. It turns out that the dynamo effect cannot be produced by the Earth’s rotation and molten iron alone, but that it is essential for about 20 per cent of the molten material to be nickel. Although conditions in the Earth’s deep interior cannot be simulated in the laboratory, the researchers were able to use advanced and highly complex computer simulations of the electron-scattering properties of many alloys of iron and nickel. The techniques employed are likely to find applications in other fields, such as chemistry, biology and technology.
In June 2018, researchers at the Universities of Liverpool, Lancaster and Oslo published in Tectonophysics details of the correlation that they had established between the motion of tectonic plates in the Earth’s crust, flow in the mantle and magnetic reversals in the core. The study suggests that slabs of dense oceanic crust take 120–130 million years to subduct through the mantle and cool the core. This actually causes the molten iron in the outer core to flow more rapidly, leading to a reversal of the magnetic field. The study proved possible because of greatly improved worldwide data regarding subduction rates and the timing of magnetic reversals.
This finding contradicts the results of a study, published in August 2017 by researchers at MIT, that only early in the Earth’s history (around 3 billion years ago) would the density of crustal rocks have been sufficiently great and the temperature of the mantle significantly higher – by some 200°C – and thus allow subducted slabs to sink some 2,800km to the bottom of the mantle. It is generally felt that nowadays subducted slabs are able to sink just 670km before the viscosity of the mantle rocks brings them to a halt.
GRAVITY AND EARTHQUAKES
In December 2017, researchers at the Paris Institute of Earth Physics demonstrated that monitoring changes in gravity created by major earthquakes could offer a rapid method of determining an earthquake’s magnitude and be superior to conventional seismic techniques. They examined records of the devastating Tohoku earthquake of 2011 in Japan, and the proposed method would have determined the earthquake’s magnitude within three minutes. Such an improvement in information would be particularly valuable in warning of a potential tsunami, which was particularly devastating in the case of the Tohoku event.
It has long been held that the largest known volcanic eruption in the last 2.5 million years, that of Mount Toba in Indonesia some 74,000 years ago, led to a volcanic winter and reduced the human population to a small remnant, creating a population ‘bottleneck’. Later humans were thought to have arisen from this tiny population. In March 2018, an international team of researchers published in Nature results of excavations in South Africa that not only positively identified volcanic tephra from Toba at the sites, but also found increased human activity after the eruption, suggesting that populations may have increased, rather than suffered a dramatic decline.
UNEXPECTED RESULT OF GLOBAL WARMING
In July 2017, a team of researchers from the Potsdam Institute for Climate Impact Research and Columbia University, New York, announced that from computer simulations they had discovered that the Sahel, one of Africa’s driest regions, could suddenly switch to a wet regime. They identified a self-amplifying mechanism that might become activated if global warming crossed the level of 1.5–2°C that had been stipulated in the Paris Climate Agreement. The research showed that the region might suddenly switch to a monsoon-type regime, with torrential rainfall for part of the year. Although this might seem to be a positive development, the change would be a major challenge to pastoralists in the region. What is noticeable is that the system has a very sensitive ‘tipping point’; any change could take place within a few years, once that point had been reached.
REVISING OUR ORIGINS?
Discoveries in recent years have cast considerable doubt upon the generally accepted view that the human species originated in eastern Africa, from whence it spread throughout the world, emerging from the region around 60,000 years ago.
In December 2017, the skeleton of a specimen of Australopithecus, known as ‘Little Foot’, was revealed to science. Although a few foot bones were initially discovered in 1980, it was not until 1992 that serious study of this fossil was initiated. Eventually, a large part of the skeleton was recovered, but it took the team of scientists some 20 years to excavate, conserve and reconstruct it. This proved to be a specimen of Australopithecus, somewhat similar to the famous ‘Lucy’ skeleton (Australopithecus afarensis) from Ethiopia, but of a different species. It has been determined that it differs from Au. afarensis and from another species, Au. africanus, and so the name Au. prometheus has been proposed. The specimen has been dated to around 3.67 million years ago, about 500,000 years earlier than Au. afarensis, and considerably earlier than Au. sediba, another example also discovered in South Africa that has been dated to 2 million years ago. Despite the almost inevitable arguments about the relationship between these species, the implication is that there were a number of them, ancestral to humans, present across a wide area of Africa.
ANCIENT HUMAN LINEAGES
The relationship between modern humans, Neanderthals and Denisovans has been subject to considerable debate. In August 2017, a team from the University of Utah published results of a new method of analysing DNA sequence data. They determined that a major split occurred hundreds of thousands of years ago in which modern humans diverged from the Neanderthal and Denisovan line. Some 744,000 years ago, Neanderthals and Denisovans diverged. The Neanderthal population grew, but they existed as fragmented, isolated populations across Europe as shown by the wide variation in the DNA sequences obtained. The study confirmed that modern Eurasians share about 2 per cent of Neanderthal DNA.
AN EXTREMELY ANCIENT CRANIUM
In June 2018, a team based at the University of the Witwatersrand published the results of a sophisticated examination of a cranium belonging to a specimen of Australopithecus, found at the Jacovec Cavern in the Sterkfontein Caves, about 40km north-west of Johannesburg in South Africa. This specimen has an age of about 4 million years and, in 1995, was described as the ‘oldest evidence of human evolution’. The recent research, subjecting the fragmentary cranium to modern high-resolution imaging techniques, revealed unexpected similarities to features found in modern humans. The team also imaged material from another extinct hominin relative, Paranthropus, dated to approximately 2 million years ago, and found distinct differences, suggesting a completely different biological origin.
MODERN HUMANS’ EMERGENCE
In September 2017, a research team consisting of scientists from Uppsala University, Sweden, and the Universities of Johannesburg and the Witwatersrand, South Africa, presented results which suggested that modern humans originated some 300,000 years ago in southern Africa. Although the genomes that they sequenced were from relatively modern individuals, they estimated that the divergence found in modern humans actually emerged some 300,000 years ago. Previously, the fossil record of East Africa suggested that modern humans originated about 180,000 years ago. However, the revised dating coincides with the dates of certain specimens (the Florisbad and Hoedjiespunt fossils) which are considered to be transitional forms to modern humans. These species were contemporary with the relatively recently discovered hominin, Homo naledi. This strongly suggests that a few species of Homo existed at the same period in southern Africa. This, in turn, would agree with the idea that various species of Homo arose in different regions of Africa at approximately the same time, rather than a single species arising in eastern Africa. It is distinctly possible that modern humans arose in several locations in both northern and southern Africa and that the modern species arose from gene flow between the different populations.
BRAIN SIZE IN ANCIENT HOMININS
Although it has long been held that human evolution was accompanied by an inevitable increase in brain size, this view has been challenged by various discoveries. In particular, research on Homo naledi published in May 2018 by researchers from the University of the Witwatersrand, South Africa, and Des Moines University in the USA, revealed that the brain of this species had many ‘modern’ features. Although the recovered skulls of Homo naledi are fragmentary, it was possible to reconstruct endocasts (casts of the skulls’ interiors) and from these to examine the structure of the brain. This surprisingly revealed that, although extremely small, the brain’s frontal lobes in particular were humanlike, and completely unlike those of the great apes, and also showed considerable difference from the features found in the brains of the primitive hominin Australopithecus. Taken with other characteristics of the skeleton of Homo naledi, this suggests that the species did indeed exhibit complex and humanlike behaviour, despite its small brain size comparable with that of Australopithecus.
THE EARLIEST AUSTRALIANS
A discovery at the Madjedbebe rock shelter, near Kakadu National Park in northern Australia, reveals that humans reached Australia at least 65,000 years ago, some 18,000 years earlier than the previously generally accepted date for any artefacts on the continent. The research was carried out by archaeologists led by Chris Clarkson from the University of Queensland and published in Nature in July 2017. Excavations at the rock shelter discovered primitive stone axes – said to be the world’s oldest such tools – and ‘crayons’ of ochre, believed to be used for artistic purposes. The dating of 65,000 years ago has wider implications than just the history of the occupation of Australia because, until very recently, the date at which humans left eastern Africa was considered to be reliably dated at just 60,000 years ago. Discoveries in other parts of the world have cast considerable doubt upon this dating, however, and this is compounded by such an early date for the settlement of Australia at such a vast distance from Africa.
THE EARLIEST AMERICANS
Analysis of the DNA from a female child, found at Upward Sun River in Alaska in 2013, reveals a date of about 11,500 years ago. More significantly, although she is related to modern Native Americans, study of the mutations that occur with time in human DNA suggests that the child was part of a previously unknown population that entered North America some 20,000 years ago. These are believed to be the first group to enter the continent from northern Asia, during the last ice age when sea levels were lower and there was a land bridge across the Bering Strait between Siberia and Alaska. The incomers were thus the ancestors of all Native Americans. The ancestral population appears to have become genetically differentiated from East Asians some 36,000 years ago, with the transition being completed by 25,000 years ago. The group of which the child was part – they have been called Ancient Beringians – remained in Alaska, whereas other humans moved on, possibly through an ice-free ‘corridor’ between the main ice sheet covering the continental interior and ice on the high coastal ranges, to colonise the rest of North America, subsequently diverging into two distinct genetic groups.
ANCIENT HUMANS IN SOUTHEAST ASIA
In a study, published in Science in May 2018, researchers from Harvard Medical School described the first comprehensive analysis of the whole genome of ancient human DNA from Southeast Asia (the area east of India and south of China). This study revealed that there has been at least three waves of human colonisation of the region in the last 50,000 years. Descendants of each of the waves of colonisation still live in the area today, and a particular surprise was the finding that there are still significant traces of the original hunter-gatherer population.
SPREAD OF THE BEAKER PEOPLE
It has long been assumed that the spread of the practices surrounding the ‘Beaker people’ and their characteristic pottery was a cultural flow, not a reflection of a migration of individuals. In 2018, however, research carried out under David Reich and Nick Patterson of Harvard Medical School used analysis of DNA from ancient human remains to show that, in Britain for example, Beaker folk replaced an astonishing 90 per cent of the pre-existing population. Earlier work by the same team had established that in the late Neolithic and early Bronze Age, the Yamnaya nomadic steppe pastoralists had migrated west and replaced some 75 per cent of the population already in western Europe.
VACCINES FROM UNUSUAL SOURCES
In July 2017 researchers at the International AIDS Vaccine Initiative and the Scripps Research Institute announced that they had discovered that cows produced antibodies to the HIV virus extremely rapidly. The antibodies were produced within weeks, whereas in humans it would take three to five years to develop the same antibodies. The discovery of an immune system that is capable of neutralising the HIV virus so rapidly offers the possibility that it may be possible to create a vaccine that causes the human immune system to create the same antibodies in a short period of time.
In August 2017, scientists at the John Innes Centre in Norfolk announced that they had made a polio vaccine in plants. They used a relative of the tobacco plant to make ‘virus-like’ particles that could be used as a vaccine. The particles were sized and shaped like the polio virus, but were empty shells and could thus not cause an infection. The technique began by using the genetic code that creates the outer coat of a polio virus, which was combined with material from viruses that infect plants. The resulting material was inserted into bacteria and used to infect the plants. These then produced the virus-like particles. The research team stated that the method was easy, cheap and rapid, and could be used to produce other forms of vaccine.
DEFEATING HEREDITARY DISEASES
Significant progress has been reported on the treatment of hereditary diseases. In December 2017 it was reported in the New England Journal of Medicine that a team from Barts Health NHS Trust and Queen Mary Hospital in London had successfully used genetic techniques to create a treatment for haemophilia. A genetically engineered virus was used to cause the patients’ livers to create the missing blood-clotting protein known as factor VIII. Although only a small trial, 11 of the 13 patients are producing near-normal levels of the all-important clotting factor, and all 13 have ceased to require haemophilia medication. Larger trials are being implemented, but the treatment appears to be revolutionary and life-changing.
Preliminary results suggest that a similar breakthrough has been achieved in the treatment of sickle-cell disease. A team at the Necker Children’s Hospital in Paris altered the DNA of a teenager so that his blood marrow created only healthy (round) red blood cells. After 15 months the teenager is no longer on any medication and is producing healthy cells.
MODIFYING DNA IN EMBRYOS
In September 2017, a team from Sun Yat-sen University in China reported that they had modified a single ‘letter’, or base, in the DNA of human embryos to correct an error that leads to the disease of beta thalassaemia. A point mutation – alteration of a single base – is the cause of the disease. The team changed a single instance of the amino acid guanine, converting it to adenine in order to correct the error. The embryos with the corrected genetic structure were not implanted. The procedure demonstrates the feasibility of curing genetic disease by directly editing the bases in DNA. In principle, it should be applicable to a range of diseases, not just beta thalassaemia, but there are, of course, considerable ethical issues to be resolved before any such technique could be employed in practice.
HARNESSING THE IMMUNE SYSTEM
In August 2017, the United States Food and Drug Administration gave approval to a new and potentially revolutionary method of combatting cancer. Treatment is ‘tailored’ to each individual patient by harvesting white blood cells from the patient’s blood. These cells are then genetically reprogrammed to locate and attack cancer. Once re-inserted into the patient, the cells search for their target and then begin to replicate. Initially, the treatment will be used for patients with acute lymphoblastic leukaemia. Although most patients respond to conventional methods, the new treatment will be applied when normal methods fail. Although there are currently known serious and deleterious side-effects to this particular treatment, the method can potentially be applied to other forms of cancer.