The Origin of the Endometrial Cell
We all know that humans have unmistakably influenced the planet, but what does that influence look like? The most familiar parts of this story are where we have most physically altered the planet. Greenhouse gasses such as CO 2 carbon dioxide , CH 4 methane , and N 2 O nitrous oxide caused by fossil fuel combustion and industrial processes are increasingly concentrated in our atmosphere, causing heat to become trapped on Earth and resulting in rising global temperatures iv. The projected estimate for mean surface temperature increase by is 6. On our current path, ice cap melt will cause sea levels to rise to levels where many major cities will be at very high risk of flooding, and natural disasters will cause damage to our communities at catastrophic levels on a much more regular basis vii.
Forests are shrinking at a startling pace — every year, we lose a swath of forest the size of Massachusetts viii.
All of these problems are exacerbated by an ever-growing human population, which has more than doubled in the last fifty years. But while climate change is one of the most visible parts of the Anthropocene, it does not paint the whole picture of our influence. Everything from damming rivers to paving roads to illuminating public spaces has changed the physical makeup of the planet in some aspect, creating a world that has truly been shaped by humans.
Human creativity has produced some incredible achievements. We have created the technology to produce high-yielding food crops with the capacity to support more human life than ever before. We can plant crops far from water sources, control the temperature inside our living spaces, enjoy leisure time and luxuries, and walk on the moon.
We have invented cures for diseases that were once catastrophic. We can travel anywhere on Earth at incredible speeds in cars, ships, and airplanes. These innovations in transportation and communication have given us the means to connect with our fellow human beings, learn about new cultures, and maintain relationships all around the globe. Access to cell phones and the internet have allowed humans to connect to and communicate with people around the globe nearly instantaneously.
Perhaps most importantly, we have self-awareness of the impact of our activities. Scientific methods can help us comprehend how emissions from our vehicles and factories are causing Earth to warm, and how that warming will affect everything from sea levels to biodiversity. We can study how the use of certain fertilizers on land will destroy marine ecosystems thousands of miles away.
We are aware of the finiteness of Earth's natural resources and can use this knowledge to analyze the short- and long-term effects of their gradual depletion. Having this self-awareness along with our creative problem-solving will be critical to helping repair some of the negative effects of the Anthropocene, and will help us to be conscious of those effects into the future. Changing climate is not a unique feature of the Anthropocene. The last six million years when hominins began to appear in the fossil record were particularly volatile and saw many different shifts in environments. The key to human survival in these settings was an extraordinary ability of our ancestors to alter their behavior and the world around them.
Our success in these times was largely due to the evolution over time of a number of traits that allowed us to be more adaptable to a large variety of environmental conditions.
Evolution - Wikipedia
The layers of sediment visible on this hillside in the Rift Valley of southern Kenya illustrate change in the environmental conditions faced by human ancestors around 1 million years ago. The first bipedal hominins were able to live both on the ground and in trees, which gave them an advantage as the habitat oscillated between forests and grasslands. The ability of early humans to make and use tools, including the control of fire, allowed them to more easily access food by scraping meat off of bones more efficiently, crushing bones for the marrow inside, and obtaining new plant foods such as nutritious tubers and roots from underground.
Tool use also enabled early hominins to diversify their diet, so they had plenty of options when certain plants and animals went extinct. And with a larger and more complex brain, early humans gained the capacity for everything from language to creative problem-solving.
These objects found in Africa illustrate the many thousands of clues discovered about human origins, including use of tools and symbols, increasing brain size, and footprints indicating walking upright. Other species in our evolutionary tree had features that were more specialized to one particular environment, and they were very successful for long periods of time in those environments.
Yet these localized features restricted their ability to live in new conditions, limiting how effectively they could inhabit new geographic zones or could adjust to unusual climatic shifts. If they were unable to adapt to new conditions or change their location significantly, they died out. A good example of that are the Neanderthals, or Homo neanderthalensis. Members of this species had bodies that were well suited for cold climates; their short, stocky bodies, large noses, and their ability to make clothing were all specialized features for successful living in the cold.
In contrast, Homo sapiens had an extremely enhanced ability to adapt their behavior to new surroundings, despite having physical features more suited for an African climate. It became particularly difficult for Neanderthals to compete with the innovative Homo sapiens , and with a geographic range limited by their specialization to cold, they eventually went extinct.
While Neanderthals and all other early human species exhibited some of the human characteristics of adaptability, Homo sapiens distinguish themselves with an extreme reliance on altering their landscapes and themselves for survival. A chart describing the relationship between early human lineages, technological innovation, and periods of strong climate variability in East Africa. The volatility of past climates does not diminish the effects of human activity in the Anthropocene.
The types of changes that we have seen in the last two hundred years are far outside the range of variability we see in the past. Examining the Anthropocene through the lens of our evolutionary history shows us that the themes of resilience and adaptability are critical to the history of our species in the past and in the Anthropocene. These distinctive traits of our lineage have created a human species that is defined by its ability to alter its behavior and environment as a mode of survival. These themes are critical to understanding how the Anthropocene has come to be, and how we will survive into the future.
We can never return the environment to how it was in the past. The conditions of the past have been so varied that there is no stable baseline on which to base what "the past" looked like. Stories of mass extinctions and the destruction of our major cities are useful tools to put the urgency of our situation in perspective. None of this is inaccurate, and it is critical that the public, and especially those in positions of power, understand the scope of influence our species has had on the planet. But oftentimes this dialogue leaves out a critical perspective: what we can do to change our behavior and environment to create a positive future.
The story of human evolution features a unique ability to adapt in the face of changing climates, and this will be no different for human-shaped climates of today and the future. With our own growing awareness of how our actions impact the natural world, the question is how best we can shape our actions so that the consequences of our activities are purposeful and positive. Altering our surroundings is fundamental to human survival.
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In this light, how may we come to alter the world that we've created in a conscious and productive way? Community and global collaboration, along with innovation, will be the keys to creating a new path for the future of our species and our environment. By looking at the Anthropocene from a human origins viewpoint, the narrative of our collective humanity and the qualities that unite us as a species with a common origin can give us a sense of communal purpose in developing solutions for the problems of the Anthropocene. These are some of the many questions that we must answer as we begin to craft the future of the Anthropocene:.
Contemplating these questions will help us begin to determine the future of the Anthropocene. The themes of self-determination, community, and action will all be parts of the human-driven innovation for the future of the planet. As we look to the future, we will see not only the planet change, but we may even see changes in ourselves as a species. We invite you to contemplate: What will it mean to be human in the future of the Anthropocene? Smithsonian Statement on Climate Change.
This cell differentiation requires the extensive reprogramming of many cellular functions, including the simultaneous silencing of cellular proliferation pathways and the activation of progesterone and cAMP signaling pathways. If implantation does not occur, the functional endometrial lining is shed, causing menstrual bleeding, another defining characteristic of the placental clade.
This transposon binds transcription factors essential for pregnancy and regulates endometrial stromal cell gene expression throughout the genome. If not small-scale changes, then what? H uman language is restricted to the human species; it is, as Noam Chomsky has observed, without any homologue in any other species. It is for this reason that children learn language easily. If universal grammar has remained invariant, so too have our musical, artistic, and mathematical abilities, as well as our general capacity for abstract thought.
These too must have been present in our common ancestor, and they must have remained unchanged ever since. The assumption that language evolved incrementally. No one has shown, even in outline, how the rules of universal grammar might have come about over thousands of generations. Recursion is a case in point.
Human beings, but not chimpanzees, are able to handle and understand such sentences. The rules that govern recursion are complex and specific. How did they evolve? David Premack expressed an understandable sense of skepticism with respect to prevailing accounts:. I t is not language alone that seems absurdly powerful. Human beings all share the potential for higher intellectual functioning.
Just as it is hard to envisage the utility of recursion on those brutal unforgiving plains, the same is true of our abilities in the fields of art, mathematics, and music. How could they have arisen by a series of cumulative steps governed by natural selection millennia before their utility was manifest? More than a century ago, Alfred Russel Wallace noted correctly that brain size is today more or less uniform across the human species.
Assuming that brain size is a marker of intellectual ability, Wallace reasoned that prehistoric man did not use his brain to its capacity.