HOMININ MIGRATION - A RESPONSE TO CLIMATE CHANGE

Up to now, I have talked about numerous ways in which climatic variations affected human evolution, often deciding about a species’ survival or disappearance. However, I have not yet mentioned a very important consequence of climate change: migration. In today’s post I will explore all the complex migratory processes triggered by a changing climate.

Migration has been a typical behavioural reaction to changing climate since early days of hominin history – hominins (namely Homo erectus) first dispersed from Africa approximately 2 million years ago (Aguirre and Carbonell: 2001). Most commonly, hominin species followed flora and fauna they depended upon, and the extent of said flora and fauna shrunk and expanded with long- and short-term variations in climate. However, movements resulting just from habitat expansion did not need any major adaptation. Evolutionarily significant migrations happened when hominins dispersed to new habitats they had to adjust to.

So, let’s go back to arguably the most important migration in our history – H. erectus going out of Africa towards Asia ~2 Ma. That movement coincided with the increase in climatic variability and the gradual shift towards cooler and drier conditions in Africa I talked about quite a lot in my previous posts. Some scientists suggest that it was the changing climatic conditions that shaped the H. erectus morphology that allowed the migration, in particular longer lower limbs that permitted long distance locomotion, but also larger body size, linear body shape and nasal morphology (Eng: 1998). In other words, first the climate triggered the hominin adaptations to arid conditions, and then the adaptations proved to be useful for long-distance migration. And then, the first hominin dispersion led to the numerous speciation events of the hominin species in different regions of the world.    

Climatic variations could have added or removed some of the physical barriers, such as deserts or ice landmasses, for people moving because of resource depletion or population growth. For example, hominin expansion to the tropics occurred during cold, glacial intervals, when the sea levels were significantly lower (Hetherington and Reid: 2010). Also, interestingly, it is likely that genetic exchange between hominin populations increased during glacial intervals as people probably gathered in refugia and new paths opened due to a lower sea level (Antón: 2002, Keates: 2004). On the other hand, the migration towards higher latitudes took place during warm, interglacial intervals.

As usual, the migratory and evolutionary processes and their relation to climate change might be much more complex than we now understand. However, the story of hominin migration as a response to environmental change teaches us a very important lesson: hominin species thrived due to their intelligence, ability to move over large distances and adapt to new territories. Migration is, after all, more efficient and reasonable response to a changing climate than the gradual  process of natural selection and genetic change. 

WHAT HAPPENED TO THE NEANDERTHALS?

Until now, I focused on how changes in climate let us develop the most human of our features: walking upright and big brains. However, I also mentioned that hominins used to be very diverse – there were numerous species living on Earth at the same time. Right now Homo sapiens is the only one present. What happened?

In today’s post I will focus on a very recent example of hominin extinction - the Neanderthals. Homo neanderthalensis was a successful species for millennia - it first appeared in the fossil record about 400,000 years ago and vanished approximately 30,000 years ago, although the exact dates are still disputed (Hublin: 2009). Unsurprisingly, the debate about who the Neanderthals were, how they lived and why they went extinct is also still open.

For a very long time the scientists thought that the Neanderthals vanished because they were outcompeted by modern humans, the Homo sapiens. Modern humans are believed to have arrived to Europe, the stronghold of the Neanderthals, about 40,000-43,000 years ago, and according to this theory they competed with the Neanderthals over resources and territory (Hetherington: 2012). Homo sapiens had several advantages over Homo neanderthalsis. For example, despite many anatomical similarities, their body build allowed them to move faster. Another important advantage was modern human’s brain, which - although smaller on average – was more developed and permitted modern humans better communication or social organisation, crucial to obtaining resources and securing territories. Some other theories claim that migrating Homo sapiens brought certain pathogens to Europe which were unknown to the Neanderthals’ immune system.

One of the most recent hypotheses states that actually the Neanderthal’s extinction as such never took place. There is evidence that modern humans and the Neanderthals interbred; moreover, recent research shows that “between one and four percent of the DNA of many humans living today originate from the Neanderthals” (Max Planck Society: 2010). This might indicate that the Neanderthals did not vanish completely, but might have been “absorbed” by the dominant modern humans (Villa and Roebroeks: 2014).

However, none of the above theories mention the climatic changes that took place at the time of the Neanderthal disappearance. The Neanderthals were a very adaptable species – they were present during both glacials and interglacials. They used to inhabit south-west Eurasia and their habitat ranged from temperate woodland to tundra. They had more body hair and fat than modern humans which made it possible for them to survive in cold conditions. But new evidence shows that when the Neanderthals started vanishing, the climate was particularly harsh, and that their disappearance occurred at different times in different regions, pushing them increasingly further south. Cold and dry weather wiped out most of the Neanderthals sources of food and turned their usual habitats into vast, open spaces that they could not adapt to. Their anatomy made them very successful in wooded areas or steppes – they could, for instance, sneak up on a prey and kill it form close proximity. They could not, however, chase the prey over long distances or throw a spear from afar. Their bodies simply did not allow it. Studies lead by Professor Tom Higham from the University of Oxford indicate that when the modern humans arrived to Europe, the Neanderthals were already in decline and the new competition was just a final blow to the declining population (Higham: 2014). They also suggest that the Neanderthals and modern humans coexisted for up to 5000 years and that the disappearance of Homo neanderthalsis was a gradual process, dispelling the theories I talked about at the beginning of the post.

As usual, it is impossible to find definite answers to all the questions we might have about our very close relatives: our dating methods aren’t accurate enough, and the fossil and proxy evidence records are still far from complete. However, it is very important to continue the research: our DNA differs from the Neanderthals by only 0.12% and we can learn some important lessons from the story of their disappearance. The latest evidence suggest that, although we are such an unbelievably adaptable species, climate change might pose one of the gravest threats to our survival. 

BECOMING HUMAN: BRAIN EXPANSION

We already established that the evolution of bipedalism was the first step towards what we perceive as being human. However, there was another process that was absolutely crucial to making the human species: encephalization, or the evolutionary brain expansion relative to body size (Hofman: 2014). This development resulted in one of the most complex and efficient structures in the animal kingdom: the human brain.

During the first 4 million years of hominin evolution, the brain growth was rather slow. More pronounced enlargement started 2.5 million years ago, most likely from a bipedal Australopithecine whose brain size was similar to that of a modern chimpanzee. The dramatic increase in the hominin brain size happened only in the last 800,000 years. Over the course of approximately 7 million years, the human brain tripled in size (Robson and Wood: 2008).  In this blog post I will try to explain what pressures could have led to brain growth, and what effects it had on the survival of our species.

When I talked about bipedalism, I said that for a very long time the leading theory of hominin evolution went more or less like that: walking upright freed our hands, free hands led to tool use and tool use resulted in a rapid growth in brain size. I also explained how we learned that this theory is unlikely. Nowadays the increase in hominin brain size is explained in two ways: through environmental or social factors.

Pressures of the physical environment

Some of the theories explaining the increase in brain size focus on the environmental selection pressures, especially climate. The rapid encephalization in hominins coincided with the period of particularly large climatic fluctuations, as shown in the figure below.

Source: http://humanorigins.si.edu/research/climate-research/effects

In order to deal with such unpredictability, our ancestors had to think ahead and develop much more sophisticated cognitive abilities in order to adapt. Some scientists say that the climate variability led to a diversification of our diet – in order to survive our ancestors had to become omnivores and come up with innovative ways of obtaining food (Willemet: 2013). Moreover, the addition of meat to their diet was a very important source of energy, much needed for the growth of brain (right now our brain is approx. 2% of our body weight, but requires at least 20% of our calorie intake to function).

Pressures of the social environment

There are also hypotheses about social factors leading to brain expansion in hominins. Population growth could have been an important factor, and it could have affected brain size in various ways. There could have been a competition for resources and consequently smarter, more innovative individuals would have better chances of survival (Falk: 1990). Alternatively, due to an increase in population our ancestors could have started to form larger, more complex social groups which involved cooperation, coalition formation or reciprocal altruism – all requiring intelligence.

The debate on the factors leading to hominin brain expansion is still ongoing and the lack of sufficient fossil evidence means we might never be certain about what actually triggered encephalization. However, there are things we know for sure: our human brains can collect, process and store unimaginable amount of information; they can find innovative solutions to problems; they can create abstract ideas. They made us the dominant species. However, there is a price to pay: our brains have enormous energy requirements, and – due to the large size – childbirth is painful and difficult for human mothers. There is no doubt, though, that it is only a small price for all the possibilities our brains give us.

WHAT FORCED US TO WALK UPRIGHT?

There are numerous theories trying to explain hominin bipedalism; however, none of them is entirely satisfactory, as each of them leaves many unanswered questions. In today’s post I will discuss the most important hypotheses of the hominin bipedalism evolution.

The earliest theory of bipedalism, suggested by Darwin in 1871 and widely supported until the 1960s, linked walking upright to the use of tools; free hands were supposed to facilitate making weapons for defence and hunting. However, fossil and archaeological records show that there is at least a 1.5 million year gap between the development of bipedalism and the earliest stone artefacts which date back to about 2.6 Ma (Harcourt-Smith: 2007). Even if we assume that the first tools were made of wood, and so weren’t preserved, the timing difference makes this theory rather unlikely.

More recent theories tend to take into account the relationship between the emergence of bipedalism and the climatic shift towards cooler and drier conditions during the Plio-Pleistocene. Initially, according to the Savannah theory, scientists thought that walking upright was an adaptation to shrinking forests and spreading grasslands. Upright posture would help to see over tall grass, reduce skin’s exposure to the sun, allow more efficient body cooling and facilitate carrying resources across open spaces.

However, as new paleontological evidence appeared, bipedalism started to be seen as one of the adaptations to the extreme climatic variability (not the encroaching savannah) in East Africa during the Plio-Pleistocene. This might be why the fossils of our ancestors show signs of both walking upright and climbing trees – such flexibility could have been crucial to succeeding in diverse habitats. This adaptation made it easier to gather food from the trees and the ground; it also facilitated carrying what was gathered over long distances.

Decreasing the dependence on trees could have favoured the development of bipedalism: some researchers believe that such a locomotion mechanism is very energy efficient on the ground.  A study published by Sockol et al. in 2007 showed that human walking needs 75% less energy than both quadrupedal and bipedal walking in chimpanzees. Then again, some other studies (like this one conducted by Halsey and White in 2012) suggest that, compared to other types of mammalian locomotion, bipedalism is similar in terms of its energy efficiency.

There is one more interesting hypothesis I want to talk about, put forward by Lovejoy in the 1980s. He argued that upright walking in humans was linked to monogamy. According to Lovejoy and his supporters, increased bipedalism facilitated carrying food to desired locations. As our ancestors became monogamous, females would choose a partner with the ability to provide plenty of food to her and their offspring. Consequently, upright-walking males would have been more likely to reproduce, passing bipedalism onto the following generations. However, this theory is quite controversial as it is unclear whether the early bipedal hominins were indeed monogamous.

It is evident that when it comes to human bipedalism, there is still a lot to be understood. Although the last 50 years were exceptionally abundant in fossil discoveries, the evidence is far from complete. There is still no clear answer or agreement on how hominins became bipedal; however, there is no doubt that the development of bipedalism was crucial to human evolution. It was fundamental to establishing our flexibility and resilience – the features that helped us become the dominant species.      

BECOMING HUMAN: BIPEDALITY

Walking upright seems so obvious and natural to us humans. In fact, the ability to walk on two legs is the trait that separated the first hominids from other four-legged apes, making bipedality one of the most fundamental human characteristics. Since the 1960s the fossil record has significantly increased, however scientists still cannot agree on why and how this radical change came about.

So let me start with what we can be the most certain about: the timeline of bipedality development. Here are some examples of the ancient roots of upright walking:

• The shape of the thigh bones of Orrorin tugenensis who lived 6 Ma suggest Orrorin was bipedal.
• The reconstruciton of the skeleton of Ardipithecus ramidus from 4.4 Ma shows extensive evidence for bipedality too.
• Lucy, the 3.2-million-year-old Australopithecus afarensis fossil, leaves no doubt for the species’ upright walking.

However, while showing signs of bipedality, all of the above species retained some features (such as long arms, short legs and long fingers and toes) indicating that they spent a considerable amount of time on trees. Homo erectus, ‘the upright man’ who appeared 1.89 Ma, was the first fully terrestrial hominid with an anatomy very similar to ours (Wayman: 2012).

What can we conclude from the current evidence then? Firstly, it suggests that the transition between quadrupedalism and bipedalism was gradual. Although first signs of walking upright appeared 6-7 Ma, it wasn’t until around 3 Ma when the early hominins became nearly as efficient at bipedal locomotion as us. They developed foot and pelvic bones which provided more support and stability for bipedal movement. The figure below represents the comparison of foot and pelvic bones between chimpanzees, Australopithecus africanus and Homo sapiens (Arsuaga and Martinez: 2006).  

 

Source: http://anthro.palomar.edu/hominid/australo_2.htm

The second conclusion we can draw is that, again, the past might have been much more complicated than we thought. We know that the hominin family tree used to be very diverse and it’s likely there was a high degree of locomotor diversity within early hominins too (Harcourt-Smith and Aiello: 2004). Different patterns of locomotion represented adaptations to a variety of habitats – which fits nicely with what I said about climate change and habitat fragmentation in my previous posts. In the next post I will explore different theories on the development of bipedality in hominins, as well as the possible relationships between walking upright and the changing climate.

WHERE DO WE COME FROM? MORE RECENT THEORIES

In the previous blog post I talked about the Savanna theory which, for a very long time, was the prevailing concept in the field of human evolution. However, more complete paleontological evidence revealed the complexity of our evolutionary journey, as well as gaps in our knowledge. In today’s post I will focus on more recent, more complex hypotheses of our origins.

In the 1980s, Elisabeth Vrba developed the turnover pulse hypothesis which expanded on already established themes (climate as a driver of evolution and an increasing aridity in during the Pliocene) while also challenging the rates of change (Kingston: 2007). In a nutshell, Vrba initially stated that speciation and extinction events were concentrated in a short period of time (also called ‘the 2.5 million year event’) due to a shift towards much drier conditions. However, the developments in paleoclimatology exposed the shortcomings of this hypothesis: current evidence revealed periods of extreme climatic variability in East Africa during the Plio-Pleistocene, which made the assumption of a smooth transition between wetter and drier conditions rather invalid. Besides, fossil evidence indicates more than one speciation event.

In the light of new evidence, Rick Potts developed the variability selection hypothesis in the 1990s. He said that the key events in human evolution resulted from increasing environmental instability rather than just a single environmental trend and change of habitat (Human Origins Program: 2014). So, this hypothesis states that hominin evolution wasn’t an adaptation to the drier climate and encroaching savanna, but to climatic variability. It argues that because of the environmental fluctuations and habitat fragmentation, habitat-specific adaptations were replaced by adaptations for versatility, such as bipedality and brain expansion in hominins.

One of the most recent ideas of human evolution is the pulsed climate variability hypothesis, developed by Mark Maslin and Susanne Shultz (Shultz and Maslin: 2013). This hypothesis is largely based on the evidence from ephemeral East African paleolakes which revealed extreme wet-dry climate cycles in the region during Plio-Pleistocene. The hypothesis suggests that major events in hominin evolution coincided with the presence of deep lakes in the region. It supports the view of climate variability being an important evolutionary driver; however, it states that climatic pulses, not a long term trend towards increased variability, drove speciation and subsequent migration events. The relationship between climatic pulses and hominin evolution is not that simple though; Maslin and Shultz mention that a significant brain expansion event, which happened ~1.8 Ma, concurred with a very wet phase in East Africa, while following expansions happened during periods of extreme aridity.

There are many more hypotheses that explain hominin evolution – I have just outlined a few. Despite increasingly complete evidence, there is still no real consensus for what drove the change.  In my view, it is very likely that climate wasn’t always the major evolutionary force and that different human features evolved through different mechanisms. The answer might lie in combining different hypotheses and acknowledging the complexities of evolution instead of trying to simplify the process and limit ourselves to one straightforward answer.

What can we take from this evolutionary discussion then? Well, on one hand we might feel relieved because if we are a result of adaptation to climatic variability, if we were ‘born from climate change’ (as stated by Mark Maslin), then we shouldn’t fear the current alterations in climate. On the other hand, we are the only Homo species left from what was once a diverse family tree which means that being adaptable does not guarantee survival. Plus, current climatic changes happen at a much quicker rate than Plio-pleistocene ‘extreme’ events. Rick Potts said:  "In the long view, the line between thriving and decline is a fine one. That is a theme of human evolutionary history" - this is what I will be exploring throughout my future blog posts.

WHERE DO WE COME FROM? THE SAVANNA THEORY

In one of my previous posts I mentioned that the records from East African paleolakes revealed huge climate variability in the region which coincided with major events in human evolution. I also talked about how this discovery changed the understating of our origins and created more questions than it answered, giving a rise to numerous theories explaining our adaptation.

Before exploring these new theories though, we need to know what our understanding of early human evolution was previously. The most popular theory was the Savanna theory which was ‘officially’ developed by Raymond Dart in 1925, but it actually started with Lamarck in 1809 and Darwin in 1871, and was still widely approved in the 1980s (Bender et al.: 2012). It was founded on the assumption that the last common ancestor of humans and great apes lived in forests, but when the global climate started cooling down and African uplift and rifting took place, the forests were replaced by patches of open woodland and grassland. According to that theory, our current form is a result of adaptations to the new habitats. As the resources became more sparsely distributed, bipedality enabled carrying of food and water over long distances. The Savannah theory also explains the hominid brain expansion by food scarcity and the necessity of complex social structure for survival (Potts: 1998). As a consequence, large brains needed more fuel so, instead of eating more plants, our ancestors turned to meat. Our bipedalism makes us one of the best long-distance runners in the animal kingdom, and little hair allows sweating and facilitates cooling. These features were adaptations to chasing animals in vast open spaces, under the sizzling African sun with no or little shade due to the lack of forests. Our advantage was not speed or strength, but the ability to run after an animal to the point it became exhausted and collapsed.     

However, recent discoveries showed us that the idea of simple transition from ape to human from is not quite right – things turned out to be way more complex than that. In the next post I will focus on some more recent, more complicated hypotheses of our origins and I will also present limits to our current knowledge.

A simplified illustration of the Savanna theory (from: toknowthyself.files.wordpress.com)

Changing climate and human evolution on the news!

A great start to a Saturday - I came across some interesting news this morning! New discovery shows evidence of a genetic ‘unity’ between the first modern humans in Europe and later peoples. The discovery challenges the current assumption that Palaeolithic hunter-gatherers went extinct during the last Ice Age. On the contrary - it suggests that some of them managed to survive the Ice Age and colonise the landmass of Europe for more than 30,000 years. Click here for details!

EAST AFRICA - THE CRADLE OF HUMANKIND

In this post I will discuss the influence of climate change on our origins. The first question we might ask ourselves here is: when and where did it all happen? And then, naturally, a more complicated question occurs: why did it happen? The answers are quite complex - scientists have spent decades exploring them – but here I will summarise the most important findings.
 

When and where?

Existing evidence suggests that the majority of hominin species originated in East Africa, and that’s why we will look closely at the climatic variations in that particular region (Maslin et al.: 2014). (In this place it’s worth noting that by hominin I mean all bipedal apes, as opposed to hominid which refers to all great apes). The question of the timing of our beginning is a bit trickier – I will treat the emergence of be the first Australopithecus species, Australopithecus afarensis, as the starting point. The figure below explains why.

Anatomical comparisons of apes, early hominins, Australopithecus, Homo erectus, and humans. Nature Education: 2012 (www.nature.com/scitable/knowledge/library/overview-of-hominin-evolution-89010983)

Early hominin evolution coincided with both global cooling and extensive tectonic changes in East Africa (Behrensmeyer:  2006). In very simple words, marine-core records (as well as long cores from deep African lakes, but we’re looking at a global picture now) indicate that a colder, drier and – very importantly – more variable climate begun 4-3.5 million years ago, triggering the climatic shift towards northern continental glacial-interglacial cycles (Trauth et al.: 2007). But, although the fossils tell us a lot about what happened and when; they can’t tell us why – it’s all down to our interpretation of the records.

Why?

There are a few factors that lead to said climatic shift and, consequently, environmental and evolutionary changes. There is no real consensus on the reasons behind the late Cenozoic intensification of Northern Hemisphere Glaciation. Some attribute it to tectonic changes, such as the uplift and erosion of the Tibetan-Himalayan plateau, the restriction of the Indonesia seaway or the emergence of the Panama Isthmus. Others relate it to the long-term decrease in atmospheric CO2. However, whatever the reasons behind it, the intensification of Northen Hemisphere Glaciation resulted in increased aridity in East Africa (Hetherington: 2012).

What’s more, such unfolding of events in high latitudes lead to the compression of the Intertropical Convergence Zone, which consequently rendered East Africa locally sensitive to orbital (precessional) forcing. In other words, it brought about extreme climate variability and the East African overall long-term drying trend was punctuated with periods of wetness.

Rapidly changing condition and dramatic variations in climate obviously had a huge influence on the environment, and as I said at the very beginning of this blog, our environment is what shapes us. No wonder many scientists believe that extreme climate variability in East Africa might have been a catalyst for evolutionary change and hominin speciation.

In the next posts I will go into detail of environmental effects of climatic changes I talked about, and I will explain their possible influence on the development of hominin traits.

For more details check:

• Behrensmeyer, A.K. (2006) ‘Climate Change and Human Evolution’, Science, 311, 5760, 476-478
• Hetherington, R. (2012) Living in a dangerous climate: climate change and human evolution, Cambridge: Cambridge University Press
• Maslin, M. A., C. M. Brierley, A. M. Milner, S. Shultz, M. H. Trauth and K. E. Wilson (2014) ‘East African climate pulses and early human evolution’, Quaternary Science Review, 101, 1-17
• Trauth, M. H., M. A. Maslin, A. L. Deino, M. R. Strecker, A. G. N. Bergner and A. Duhnforth (2007) ‘High- and low-latitude forcing of Plio-Pleistocene East African climate and human evolution’, Journal of Human Evolution, 53, 475-486

LIFE, TIME AND CHANGE

In the previous post I mentioned the Darwinian concept of evolution which widely disturbed the 19^th century mindset. Today I’d like to explore the idea a little bit more, and challenge it.  

In simple words, Darwin stated that organisms within the same species vary and that the offspring inherits a part of that variation. He believed that the individuals that are more compatible with their environment are more likely to survive and pass on their variants. Consequently, better-adapted traits accumulate and shape species through natural selection.

So according to Darwin’s idea (and related theories of gradualism), the processes of evolution are slow but continuous. This hypothesis also suggests that highly adapted, dominant species resist novel change, which means that if a significant environmental alteration occurs, dominant species might simply go extinct. Although gradualists do have a point, they fail to account for species adaptability to catastrophic events and rapid environmental change.

The concept of punctuated equilibrium attempts to fill in that gap in the gradualist hypothesis. It states that there are very long periods of environmental stability (or equilibrium), where no change in species occurs. Those stable periods are ‘punctuated’ by environmental crises or catastrophic events, which stimulate rapid genetic, physiological and behavioural changes.

To make the two concepts clearer, here is an illustration:

Gradualism (a) and punctuated equilibrium (b)

At the moment, there are also a few other theories on the rate of evolution which try to combine both gradualism and punctuated equilibrium. However, neither hypothesis is considered more correct than another and, funnily enough, the fossil evidence is used to support both. In my view, it is very likely that the reality is more complex than our ideas, and that the rate of evolution varies with time, location and species.

Despite the ambiguity, understanding the concepts of gradualism and punctuated equilibrium is essential for the readers of this blog. Firstly, it helps us explain the evolutionary journey towards our current form, and secondly – maybe more importantly – it can give clues as to what will happen to us in a changing climate.  

If you want to read on the theories in more detail, here are some useful resources:

• Gould, S. J. and N. Eldredge (1977) ‘Punctuated equilibria: the tempo and mode of evolution reconsidered’, Paleobiology, 3, 2, 115-151
• Saylo, M.C., C. C. Escoton and M. M. Saylo (2011) ‘Punctuated Equilibrium vs Phyletic Gradualism’, International Journal of Bioscience and Biotechnology, 3, 4, 27-41

And my personal favourite (pages 315-330 are relevant to this post, but the whole book is worth reading):

• Van Andel, T. H. (1994) New Views on and Old Planet, Cambridge: Cambridge University Press

ENVIRONMENTAL CHANGE – DEFINING WHAT IT MEANS TO BE HUMAN

Understanding of the origin, evolution and disappearance of species only began in the 19th century – which, in the grand scheme of things, is fairly recently. To many at the time the concept appeared ridiculous and unacceptable. The idea of humans and apes sharing a common ancestor met with the public outrage; it somehow stripped us from our humanity and it went against the view of people being much more than just an animal species. It seems to me that the 19^th century public ridiculed the idea of evolution largely because of the fear it provoked. Not only did it raise numerous daunting questions, it also introduced a new, scary notion of humans not being as special as they thought they were and – what’s worse – humanity not being set in stone.

Punch Almanack: Man is But a Worm (1881)

Fortunately, nowadays a vast majority of us feel comfortable with, and even fascinated by, our origins. We are fully aware that the current climate and the environmental conditions associated with it fluctuate in time. We also know that when the environment starts to changes, organisms have two ways to avoid extinction: migrate in search for preferred habitat or adapt by genetic change. We accept the fact that the concept of humanity has taken its shape gradually over millennia.

In my blog, I will attempt to reconstruct the evolutionary journey that brought us to where we are now. I will try to explain how the climate-driven environmental variations forced us to walk upright, make tools, develop complex mental and social behaviour, or depend on technology to alter our surroundings. Finally, I will explore the ways in which climate change defined humanity and, perhaps more importantly, I will investigate what current rapid climatic changes mean to the future of our, so far versatile and adaptable, species.