The speed of evolution can be defined as the number of generations required for an initially random population to reach a specific evolutionary target or adapt to a defined goal. There are a number of factors that affect the speed of evolution, and many do not act in isolation. New research suggests that the speed of evolution is actually taking place up to four times faster than previously thought.
Genetic Variation
Mutation rates, gene flow and sexual reproduction are just some of the genetic factors that affect the speed of evolution. Mutations are often key to introducing new genetic variations that lead to different organism traits. If these traits prove to be advantageous, natural selection can help those organisms to proliferate. Gene flow – the exchange of genetic material between diverse populations, often facilitated by migration and reproduction – further increases adaption to changing environments.
An example can be seen in the peppered moth, which exists in both light and dark colours due to a genetic mutation. During the Industrial Revolution, increased pollution darkened the trees in surrounding areas, giving a distinct advantage to the dark-coloured moths with the mutation, which then became more common in the population.
Population Size
Small populations, which can result from environmental constraints or natural disasters, are often subject to evolutionary disadvantages. Genetic drift – a concept where genetic material is passed on by chance as opposed to natural selection – plays a larger role in smaller populations. Harmful materials are also more likely to be passed on through inbreeding, however, with smaller groups more likely to experience faster evolutionary changes.
Around 10,000 years ago, cheetahs experienced a population bottleneck which reduced their genetic diversity and gave rise to genetic drift. Today, cheetahs experience low genetic diversity, which have given rise to genetic defects and reduced fertility.
In larger populations, genetic drift plays a less significant function, as natural selection takes on a more dominant role. Larger populations tend to act as a larger repository of genetic diversity, which can enhance adaptability, although the rate of evolution is far slower due to greater genetic dilution.
Environmental Factors
Environmental factors play a key role in the rate of evolution. Stable environments tend to result in slower rates of evolution due to less pressure to adapt, while fluctuating environments often drive rapid change in order to promote survival. Crocodiles have existed for over 200 millions years but have physically remained largely unchanged. Small changes in their river environments, temperature and food availability have led to a fairly consistence genetic diversity.
Coevolution is another key factor, often observed in predator-prey dynamics. In these interactions, evolutionary “arms races” occur, with each species rapidly evolving in response to the other. Additionally, human intervention has artificially accelerated evolutionary traits through selective breeding.
With the dawn of December sees the inevitable arrival of festivities; everything from carols and decorations to jolly jumpers make an appearance for this special time each year. However, one of the most significant signs of Christmas time is the presence of festive foliage. It may be that prickly green holly adorns your Christmas pudding, mistletoe dangles from your doorways, or you have a Norway Spruce dressed to impress in the living room. What makes these plants so seasonally significant?
Christmas Tree, Oh Christmas Tree
Perhaps the most obvious, and largest, festive flora is one of the best-known types of Christmas tree, the Norway Spruce. For those who opt for a real tree every year, this tree’s rich pine aroma and deep green foliage is irresistible, and characteristically Christmassy.
Originating in Germany, the tradition of decorating Christmas trees began with devout Christians in the 16th century, who brought trees into their homes, or even built Christmas pyramids of wood and decorated them with evergreens. But it wasn’t until 1846, when Queen Victoria and her husband, Albert, were sketched with their family around a Christmas tree in Illustrated London News that it become popularised.
A Holly, Jolly Christmas
With its vivid red berries and glossy green leaves, Christmas wouldn’t be complete without holly boughs adorning windows, doors and baked festive treats. These iconic Christmassy hues are what make the plant especially significant to the festive season. According to Elizabeth Abbess in How Stuff Works (2024), Christians adopted the holly tradition from the Druids, who believed holly to be a symbol of eternal life and fertility. Christians regard it to symbolise Jesus Christ due to the red berries, representing the blood shed at his crucifixion, and its pointed leaves, symbolising the crown of thorns placed on Jesus’ head on the cross.
Mistletoe Moments
This romantic evergreen features forked branches and clusters of white berries with a frosty finish, making it wintry and wonderful. Its association with love originated in ancient folklore, when Druids would embrace beneath mistletoe growing on trees, while the custom of kissing under mistletoe was first recorded in a song in 1784 in an English musical comedy. This tradition still remains today, bringing the joy of love and romance to the holidays.
Legendary Poinsettias
With scarlet tones and large leaves, this beautiful plant is bountiful at Christmas. Its festive significance isn’t just down to its red tones; originating in Mexican lore, a young, penniless child, Pepita, picked a bouquet of weeds for Jesus, unable to afford anything else. The angels sympathised, and transformed her weeds into beautiful red flowers, solidifying red and green as iconic Christmas colours. Despite appearances, their red halo is not made of petals, but rather a leaf called a bract, which is long-lasting, even in winter.
Time To Tuck In
Christmas wouldn’t be complete without festive feasting, which includes cranberries as a staple. Whether paired with a roast turkey dinner, or spread into a sumptuous sandwich, cranberries are a seasonal necessity. They are native to North America and despite their bitter taste, they are often preserved with sugar as a sweet accompaniment to savoury meals. Aside from its diverse flavour pairings, its rich redness also makes it popular and striking in decorations, too. This multipurpose berry is wonderfully versatile, perfect for Christmas celebrations.
References:
Abbess, Elizabeth. (2024) Why Do We Decorate with Holly at Christmas? How Stuff Works.
History.com Editors. (2023) History of Christmas Trees. History.
Mchale, Ellen and Young, Katherine. (2024) 12 Plants of Christmas. Royal Botanic, Kew Gardens.
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Viruses often have a bad rep; they are associated with words like “pandemic”, “disease” and “contamination”. They are, however, an essential part of life and have a surprising and increasingly evident role in the carbon cycle. New evidence points to their part in the fight against climate change; with increased understanding, we can influence how viruses improve our natural carbon sinks and counterbalance atmospheric carbon increases.
Viruses And The Ocean Carbon Cycle
Marine based phytoplankton and bacteria are responsible for producing approximately 50% of the world’s oxygen. They also play an important part in carbon fixation. Viruses infect a large number of these microorganisms, causing their cells to rupture in a process known as a “viral shunt”.
The “viral lysis” of microorganisms causes a large release of carbon and organic matter back into the aquatic food chain. Oceans typically absorb 25% of atmospheric CO2 but the viral shunt impacts their ability to carry out this sequestration process by recycling carbon back into the upper ocean. Some viruses interestingly carry genes that enhance carbon fixation and the ocean “carbon pump” process by boosting photosynthesis in cyanobacteria, even as the cell is breaking down.
Viruses And Soil Carbon Sequestration
Our soil stores more carbon than the atmosphere and world’s plant life combined and there are hundreds-of-millions to billions of viruses in each gram. Scientists are now starting to fully understand the vital roles viruses play in soil carbon storage. Similar to the oceans, the viral shunt effect can play a vital role in the level of soil-based carbon as well as its microorganism composition.
Viruses selectively infect microbial populations; they may target fast growing bacteria that allow those that contribute more effectively to carbon fixation to flourish. Depending on circumstances, this process can either increase carbon soil retention or lead to higher levels of carbon release, playing an important part in how ecosystems such as peatland (pictured) respond to climate change.
Regulators Of Ecosystem Carbon Dynamics
Viruses play an often-underestimated role in land and ocean carbon storage. They achieve this through the control of microbial populations and the viral shunt process. By better understanding the role of viruses in the carbon cycle model, scientists will be able to increase the accuracy of ecosystem responses to environmental changes such as temperature rises and nutrient depletion. This would be especially important within environments such as wetlands or areas of permafrost.
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Our planet is teeming with an incredible variety of life, but this biodiversity is not spread evenly. Certain regions—known as biodiversity hotspots—are home to a remarkable concentration of species and ecosystems. In fact, there are 36 recognised biodiverse hotspots, and to qualify as one, an area must meet two specific criteria set by the Critical Ecosystem Partnership Fund (CEPF), a joint global body committed to protecting biodiversity. These are: To
contain at least 1,500 species of vascular plants found nowhere else on Earth (known as “endemic” species); To
have lost at least 70 percent of its primary native vegetation.
These biodiverse areas have fascinated scientists and explorers for centuries. Perhaps the most famous example is Charles Darwin, who visited the Galápagos Islands in 1835. His observations of the islands’ unique species played a key role in developing his theory of evolution by natural selection, making the Galápagos a perfect place to start.
Galápagos Islands and Darwin
These volcanic islands, which are part of Ecuador, exist off its coast and comprise only 5.3% of the Earth’s land area, yet they house an incredible 20% of the world’s biodiversity. The Galápagos Islands also have high levels of endemism, meaning many species are found nowhere else on Earth. Latest estimates suggest that over 80% of land birds and 97% of reptiles and land mammals here are endemic. Many species remain undiscovered!
Madagascar and the Indian Ocean Islands
This isn’t just a place famous because of the popular kids’ movie, Madagascar, it’s renowned for its exceptional biodiversity. Located off the southeastern coast of Africa and separated from the mainland by the Mozambique Channel, Madagascar boasts many endemic species, just like the Galápagos. It’s the fourth-largest island in the world (after Greenland, New Guinea, and Borneo) and hosts 12,000 species of vascular plants (for comparison, the UK has around 2,500), 1,000 species of orchids (the UK has around 57), and 278 species of amphibians (the UK has only 7). If you’re a fan of frogs, orchids, or plants, this is the place to be!
Amazon Rainforest – The Biodiverse Lungs of the Earth
The Amazon is one of the most iconic wildernesses in the world, frequently featured in movies and documentaries—and for good reasons. Covering 40% of South America, it’s home to one-third of all species on the planet, including 2,000 bird species. Known as the “Lungs of the Earth,” it plays a critical role in processing carbon dioxide into oxygen through its 40,000 plant species.
Monteverde Cloud Forest – Costa Rica
Costa Rica may be familiar to you as it referenced in the novel and film “Jurassic Park,” but while it’s incredibly biodiverse, it lacks the dinosaurs! The Monteverde Cloud Forest is unique because its treetop canopy is constantly immersed in low-hanging clouds, which slow evaporation and create a rare, moisture-rich environment. This environment supports a massive amount of biodiversity, especially among epiphytes like lichens, orchids, and bromeliads, which grow on other plants without harming them.
Indonesia spawned Wallace’s Theory of Evolution
Shifting from South America to Southeast Asia, Indonesia is another exceptionally biodiverse region. This archipelago of over 17,000 islands combines both terrestrial and marine ecosystems. It contains part of the third-largest rainforest in the world and is home to extensive coral reefs. Indonesia boasts the most mammal species of any country, the second-highest number of fish species, and the third-highest number of bird species. The lesser known but still pioneering Alfred Wallace developed his own theory of evolution whilst exploring the Indonesia Archipelago at the same time as Charles Darwin was doing so in the Galapagos islands.
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As seasonal temperatures drop in late autumn and the days shorten in the lead-up to the solstice, animals such as squirrels, mice and bats enter a state of hibernation. Hibernation itself is thought to be triggered by reduced temperatures and declining light levels. Hedgehogs, for example, must reach a hibernation weight of between 500 and 700 grams, and the average temperature must drop to around 5°C before they begin hibernating.
During the preceding months, these animals intentionally overeat to build up fat reserves. Once winter sets in, they retreat into their dens and enter a state of near inactivity, enduring the coldest, harshest weather. Some animals also store non-perishable food in their dens, waking intermittently to eat. This hibernation typically lasts 4 to 6 months, depending on the species and the severity of the winter.
While we often take this hibernation process for granted, it is a biologically complex phenomenon, and something humans are not even capable of. Hibernation is a prolonged state of torpor, where metabolic activity is suppressed to less than 5% of normal levels. This drastic reduction in metabolic rate allows animals to conserve energy and stretch their fat reserves and food stores throughout the winter months.
Temperature Regulation And Extreme Cooling
Hibernating animals lower their body temperature by an average of 5 to 10°C. The arctic ground squirrel, however, exhibits the most extreme example of this adaptation, cooling its body to sub-freezing temperatures. This remarkable ability is believed to be managed by levels of adenosine in the brain, a neurotransmitter that increases in ground squirrels during winter. Their brains have been shown to become more sensitive to adenosine, helping to trigger this extreme cooling.
Slowed Heart Rate During Hibernation
Another key feature of hibernation is a dramatically reduced heart rate. For instance, a hedgehog’s normal active heart rate of around 190 beats per minute drops to just 20 beats per minute during hibernation. One of the lowest recorded hibernating heart rates belongs to the dwarf lemur of Madagascar, one of the few regularly hibernating primates. Its heart rate drops from a rapid 300 beats per minute to just 6 beats per minute.
Minimal Brain Activity
Breathing also slows significantly during hibernation. Instead of taking a breath every second or two, hibernating animals may go as long as 10 minutes between breaths. In the dwarf lemur, brain activity becomes nearly undetectable during this state. However, they are far from brain-dead. By definition, brain-dead animals wouldn’t be able to wake up. Interestingly, hibernating animals don’t even display typical sleep patterns. Their brain waves more closely resemble a waking state, albeit greatly suppressed. In fact, when they finally awaken from hibernation, they often need a prolonged period of actual sleep to recover.
Hibernation is a fascinating and complex survival strategy that allows animals to endure the harsh conditions of winter by drastically reducing their metabolic functions.
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Scientific Advances Made Aboard The International Space Station
I was captivated by the recent news about the two astronauts stranded on the ISS due to their Boeing Starliner being deemed unfit to return them to Earth. Their initial 8-day stay has now been extended to last until next February, as there is no available spacecraft to bring them home until then. This ongoing space saga will see Boeing’s competitor, SpaceX, coming to their rescue. NASA is eager to resolve the situation as quickly as safely possible, so that it can fully focus on its primary strategic objective: decommissioning the ISS, which is approaching the end of its operational life. By 2030, it will be steered out of orbit to break up in a destructive, fiery re-entry.
Thankfully, the legacy of this football-pitch-sized floating laboratory will endure. NASA plans to continue the ISS’s work by distributing its various activities across newly launched space stations before the 2030 end date.
Before the ISS project transitions into its next phase, it’s fitting to highlight the scientific breakthroughs that have occurred aboard the ISS since its inception.
1. Impact Of Microgravity On Muscle And Bones
Research on the ISS has shown that the human body can lose 1% to 2% of bone and muscle mass per month while in space. ISS scientists have also explored mitigation strategies, involving the use of resistive exercise devices (treadmills and workout stations), nutrition, and drugs that can significantly reduce bone loss. This research has the potential to improve osteoporosis treatments and prepare the body for long-range space travel.
2. Protein Crystallography
Protein crystallography is one of the most effective techniques for understanding the shape of human protein molecules, a crucial step in developing effective medicines. On Earth, growing such crystals in a fluid is hampered by gravity-driven convection, causing denser particles to settle at the bottom of the fluid vessel—a problem that keeps biochemists up at night! However, in the microgravity environment of the ISS, these crystals can grow to much larger sizes, making them easier to analyze. This has led to the development of novel treatments for conditions like cancer and muscular dystrophy, to name just a few.
3. Examining The Fifth State Of Matter
Just over two decades ago, researchers on Earth created a completely novel fifth state of matter, called a Bose-Einstein condensate (BEC) which has quantum properties. This is achieved by cooling particles to near absolute zero ( – 273 degrees Celsius) . Six years ago, scientists in NASA’s Cold Atom Lab were the first to create this fifth state of matter in space. This discovery should lead to significant breakthroughs in the understanding of quantum mechanics.
4. Advanced Life Support Systems
Developed and tested on the ISS, the space station’s life support system was designed to provide clean air and water to the crew. It purifies the station’s water, recycling 93% of the water used onboard. This advanced, compact water filtration technology has since been licensed for use on earth for water treatment. Such systems are essential for deep space travel and can be used to provide clean water in at-risk areas where clean water has become inaccessible.
5. Monitoring Earth From A Unique Perspective
Crew handheld camera imagery has enabled the ISS to actively contribute to orbital data collection, aiding disaster response activities around the world thanks to its unique panoramic viewpoint. Additionally, the ISS is equipped with SS-HDTV cameras that capture night images of Earth, helping to determine if power has been restored to cities after a disaster. The Lightning Imaging Sensor (LIS) detects the distribution and severity of lightning, improving severe weather forecasting. The ISS’s inclined low-Earth orbit complements weather satellites in higher-altitude polar orbits. Instruments like ECOSTRESS can analyze water stress in plants, while GEDI can assess carbon stores in forests.
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How And Why Leaves Turn Red And Yellow In The Autumn
With the 22nd of September marking the Autumn Equinox, we know the season is now upon us. But this is more than just a date; it’s driven by solar orbits and our relative positioning to and distance from the sun. This leads to longer days, higher temperatures and more intense UV radiation in the summer and less in winter.
Why Are Leaves Green In The First Place?
It is these physical effects that explain the green leaves that we observe on trees throughout the summer. During the spring and summer, the biochemical substance known as Chlorophyll dominates leaf chemistry. Its purpose is to absorb the energy from the Sun to create energy-storing molecules in the form of sugars. During this process of photosynthesis, Chlorophyll absorbs blue and red wavelengths and reflects green light, which is why it appears green.
Why Do The Leaves Change Colour?
As the temperature drops and the days shorten in Autumn, the leaves begin to receive less UV radiation from the sun, which triggers the breakdown of Chlorophyll. The tree does not replenish the Chlorophyll, and other chemicals start to dominate leaf chemistry. The beautiful yellow and orange leaves that we see in Autumn come from the xanthophyll and carotenoids, (now free from the masking effect of chlorophyll) which have a yellow and red pigment.
However, one of the striking botanical sites of Autumn is the fiery red leaves, also explainable by physics. This occurs in specific species of tree in years when there has been lots of sunlight and dry weather, meaning photosynthesis has been super-charged and there are very high concentrations of sugar in the tree sap. This causes the tree to produce anthocyanins, which have a red pigment, to rapidly extract the sugar from the leaves before they fall, to maximise energy reserves for the winter.
Once this process is over, the leaves die, and trees shed them as these leaves are unable to produce energy. It also makes way for new growth in Spring and the start of the new energy transducing system of photosynthesis.
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Our Changing Weather
As the UK grapples with the impact of climate change, one noticeable effect is the shifting patterns of our weather. Historically known for its temperate climate with distinct seasons, the UK is now experiencing increasingly unpredictable weather, with summers extending into September and beyond. Understanding these changes is crucial for adapting to new weather norms and preparing for the future.
Extending Summers: A New Norm?
One of the most evident changes in the UK’s weather patterns is the extension of summer. Traditionally, summer in the UK spanned from June to August, but recent trends show that high temperatures and dry spells are increasingly extending into September and sometimes even October.
According to the UK Met Office, the past few years have seen notably warm late summers. For instance, in September 2023, the UK experienced a particularly warm month, with temperatures reaching 22°C, which is above the average for the time of year. This follows a trend observed over the past decades, where September temperatures have been consistently higher than the historical averages.
1. Increasing Temperatures
Data from the Met Office highlights a significant warming trend. The UK has seen an average temperature increase of approximately 1.2°C since the pre-industrial period. This warming has led to more frequent and intense heatwaves. For example, the summer of 2022 was one of the hottest on record, with temperatures exceeding 40°C in some areas.
2. Changing Rainfall Patterns
Climate change is also affecting rainfall patterns in the UK. Research indicates that while summers are becoming warmer, they are also experiencing fluctuating precipitation levels. The Environment Agency reports that the UK has seen a reduction in summer rainfall by about 15% over the last 50 years. This change is leading to drier, more drought-prone conditions during summer months, followed by intense rainfall during other periods, contributing to increased flooding risks.
3. Shifting Seasonality
Seasonal patterns are becoming less predictable. A study by the Centre for Ecology & Hydrology shows that spring and autumn are extending, while winter and summer are becoming more extreme. The length of the growing season has increased by about 10 days over the past three decades, reflecting these shifts.
Implications and Adaptations
1. Impact on Agriculture
Extended summers and shifting seasonal patterns have significant implications for agriculture. Farmers may need to adapt to longer growing seasons and altered precipitation patterns. The UK Department for Environment, Food & Rural Affairs (DEFRA) suggests that crop selection and farming practices will need to evolve to address these changes, ensuring that crops can withstand prolonged heat and variable rainfall.
2. Energy and Infrastructure
The energy sector also faces challenges due to these changing weather patterns. Prolonged heatwaves increase the demand for cooling, while shifting rainfall affects water resources used for cooling power stations. This can lead to droughts and water shortages. Infrastructure, too, must adapt to handle extreme weather events, such as increased flooding and heat stress on roads and buildings.
3. Public Health
Extended heatwaves pose health risks, particularly for vulnerable populations (the elderly and very young). The UK Health Security Agency (UKHSA) highlights that prolonged high temperatures can lead to heat-related illnesses, such as heat exhaustion and heatstroke. Public health strategies need to address these risks, with increased awareness and preparedness measures.
Looking Ahead
As the UK continues to experience changing weather patterns due to climate change, it is essential to stay informed and adaptable. The trends of warmer, longer summers and shifting precipitation patterns underscore the need for comprehensive planning and response strategies across various sectors.
By understanding these changes and their implications, we can better prepare for the future, making informed decisions that mitigate the impacts of climate change and protect our environment, health, and infrastructure. The evolving climate is a challenge, but with proactive measures and continued research, we can navigate these changes effectively.
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Planet Of The Apes… Or Not?
The hugely successful, fascinating movie franchise Planet of the Apes charts a human (Homo sapiens) apocalypse and subsequent rise to prominence of apes (Hominidae). But if humans were to die out, would apes really become the dominant species, or would it even be another?
Other Claimants
Ardent zoologists writing on the BBC’s Science Focus portal argue that humans are not the dominant species and never have been. They explain that ants are far more numerous than humans, trees have much longer lifespans, and fungi have a combined weight greater than the entire human race. However, given these varied criteria for dominance—population size, lifespan, planetary mass—they crowned bacteria as the true rulers, classifying them as the dominant life form. It makes sense when you think about it: bacteria existed 4 billion years before us, they created the oxygen in the atmosphere, and they outnumber us by a thousand quadrillion to one (10 27). The combined mass of bacteria outweighs all animal life, and they inhabit a much larger biosphere than humans, living everywhere from the stratosphere to the ocean floor. Bacteria regularly overwhelm our immune systems and antibiotics, killing hundreds of thousands of us every year. Bacteria were dominant before us and will remain so even after humans are gone.
Macro-organisms
Fair enough then, bacteria are winning, but what about macro-organisms? Would apes become the dominant macro-organism if humans die out? It’s still unlikely because it’s been argued that any event resulting in human extinction would likely impact the fragile and small populations of physiologically similar apes, even more severely and potentially more quickly than us. Zoonotic diseases, solar radiation, a new apex predator—these threats would affect apes as well. Our fates are most likely tied together, and given our technological advantages, apes would probably succumb to an existential threat before we did.
Films like Day of the Triffids and Video Game / TV Series The Last of Us have suggested that carnivorous plants and intelligent fungi could become the new apex predators, but there’s not much science to support this. The reality is that we don’t really know which species would become dominant. It would depend on the specific cause of human extinction. For example, if excessive heat, radiation or food scarcity were to kill off humans, then life forms—whether plant or animal—that can best adapt to these conditions might become dominant. This could be an existing species or a newly evolved one.
So, the extinction of humans is unlikely to lead to a Planet of the Apes scenario. It’s more likely to result in a “planet of the species that best adapts to the apocalyptic event” or “planet of a newly evolved species”. But that doesn’t make for a very catchy film title.
How Did Humans Become The Dominant Species On Earth?
Now, arguably, bacteria are the dominant species on Earth, but I have discussed that elsewhere and won’t repeat myself here. Instead, I’m curious to explore how, after bacteria, humans became the dominant species on Earth.
For a long time, paleontological evidence (or the lack of it) led scientists to believe that dinosaurs and prehistoric humans did not coexist. However, science has evolved, and new molecular data from a groundbreaking collaboration between scientists from the University of Bristol and the University of Fribourg suggests that placental mammals (including humans) did briefly coexist with dinosaurs before the dinosaur extinction event. Nevertheless, the scarcity of paleontological evidence implies that the hostile cretaceous period environment likely limited human numbers.
This discovery updates the narrative of how humans became the dominant species. When the asteroid struck Earth 66 million years ago, causing a mass extinction event, it wiped out the dinosaurs, which were a major competitor to early mammals. This allowed mammals, including our prehistoric ancestors, to thrive in a post-dinosaur world. Prehistoric humans began to rise up the food chain thanks to several important and unique features: binocular vision, dexterous fingers, superior intelligence, social skills, and the use of tools. These attributes enabled us to hunt and farm other animals, becoming the apex predator. They also allowed prehistoric humans to adapt to environmental changes, exert control over their surroundings, and maintain their position at the top of the food chain.
The group of prehistoric humans known as hominids consisted of several species, including Homo erectus, Homo habilis (Neanderthals), Australopithecus, and Homo sapiens—the latter being our species, and the only one that exists today. Our status as the only surviving hominid species was likely not the result of some war for dominance between the different hominid species. Instead, hominid populations emerged and expanded faster across Africa, connected through trade and social networks. About 50,000 years ago, Homo sapiens established itself as the dominant hominid species, likely due to our superior ability to adapt to various conditions across the Earth, thanks to increased cognitive function.
In the end the natural historic part of our rise to dominance is not particularly dramatic, in the theatric sense—it is more National Geographic docu-channel content than Hollywood blockbuster material.
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Deoxyribonucleic acid (DNA) is one of the most important molecules in all living things; it contains a unique sequence of information needed for life. There are in fact over 3 billion sequences in the human genome which are responsible for our genetic makeup. Each DNA strand would measure 2 metres in length once unravelled and serves an important purpose in protein synthesis, heredity and evolution.
DNA Structure
DNA was discovered in 1953 by Francis Crick and Jim Watson. Their research was significantly aided by Dr Rosalind Franklin’s research and famous Photo 51 of DNA’s signature double helix, allowing Crick and Watson to complete their molecular model.
We can think of DNA as a large book containing all of our genetic information. This is known as our genome. DNA is made up of a very long double helix of paired nucleotides. Each nucleotide contains one of four bases – adenine with thymine and cytosine with guanine. They form the rungs of the DNA ladder with each base pair making up the ‘letters’ of our book. The order of these letters form sequences known as genes which can be thought of as ‘paragraphs’. It’s these sequences that make each person and organism unique. In each cell, our entire DNA sequence is broken up and stored into 23 separate pairs of chromosomes, forming the ‘chapters’ of our book.
Role of DNA
DNA serves as a store for all of our genetic information. It has the ability to replicate itself in order to ensure that when our cells divide, the new cells contain a perfect DNA copy. DNA carries out protein synthesis through the process of transcription. When a gene is ‘switched on’, a molecule called RNA polymerase attaches to the start of the gene sequence and unzips the DNA double helix into two single strands. A messenger RNA (mRNA) copy of a DNA gene sequence is synthesised as free bases attach to one of the single stands in a complementary fashion. Once the gene sequence has been fully read, the mRNA is processed – sections of mRNA are removed or added.
Within humans, the mRNA leaves the nucleus of a cell into the cytoplasm where protein production molecules called ribosomes produce an amino acid chain based on the mRNA sequence. The completed amino acid chain is then released to form a protein molecule. The sequence of amino acids within the protein determines its structure and function, which ultimately determine an organism’s characteristics and traits.
Human Evolution
By determining our features and characteristics, DNA plays an important part in evolution and heredity. Organisms inherit unique traits from their parents through the process of reproduction; here each offspring contains one half of each of their parents DNA to create a new genetic makeup. This process creates genetic diversity in a species which can aid its adaption and survival. It is interesting to note that all humans are 99.9% identical to each other – it’s this 0.1% difference in our makeup that makes us so unique. Scientists are able to compare DNA sequences within humans to understand our genetic ancestry, migration patterns and evolution.
Genetic Advancements
Modern day medicine and genetic discoveries have heightened our understanding of the human genome. DNA errors or mutations which can lead to diseases and genetic disorders can now be addressed through techniques such as gene therapy. As our understanding of DNA increases, so will our ability to improve our health through personalised medicine, precision agriculture and environmental conservation.
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