How do people change landforms negatively

Humans have been influencing the ecosystem for thousands of years

Natural landscapes have long ceased to exist

Landscapes untouched by humans are nowhere on earth, and - with a few exceptions - have not been for thousands of years. This is underlined by a recent study published in the journal PNAS under the direction of Nicole Boivin, Director at the Max Planck Institute for the History of Man and a scientist at Oxford University. The comprehensive synopsis of archaeological data from the last 30 years provides information on how humans have shaped the earth's landscapes for millennia through hunting, agriculture and trade. The data also show the profound influence of humans on the distribution of animal and plant species worldwide.

The findings of the international research team suggest that the previous debates on nature conservation without archaeological knowledge are missing an important aspect. According to the authors, it is a misjudgment that societies before the industrial revolution had little influence on the environment or the diversity of species. The publication is based on current data sets of historical DNA and RNA, stable isotopes and microfossils as well as on new statistical methods and computational methods. Many of the most common plant and animal species found today were favored by our ancestors; conversely, hunting and changes in land use led to the extinction of many species thousands of years ago. The research team concludes that, given this and other evidence of long-term anthropogenic change, we should seek pragmatic conservation solutions rather than the unattainable ideal of “natural conditions”.

The study names four main phases in which humans changed the world around them in such a way that it had profound effects on ecosystems: the global expansion of humans in the late Pleistocene, the Neolithic spread of agriculture, the era of island colonization People and the emergence of early urban societies and global trade relationships. The scientists rely on fossil finds that show that modern humans (Homo sapiens) lived in East Africa around 195,000 years ago and spread to the most remote corners of Eurasia, Australia, North and South America 12,000 years ago. This far-reaching settlement of the planet is associated with the extinction of numerous species. In the period between 50,000 and 10,000 years ago, around two thirds of the around 150 large animal species (megafauna) living at that time disappeared. Perhaps the most significant species extinction, according to the study, had "dramatic effects" on the structure of ecosystems, the availability of nutrients and the distribution of seeds.

Huge numbers of farm animals

The second phase, the global emergence of agriculture and livestock, created new evolutionary pressures on plants and animals. These pressures had lasting effects on the distribution of species on an unprecedented scale. The domestication of sheep, goats and cattle is given as an example. These animals were first kept in the Middle East 10,500 years ago and from there reached Europe, Africa and South Asia in a few millennia. Another study highlighted in the review points to chickens that were originally domesticated in East Asia and reached Britain in the second half of the last millennium. Today the number of chickens living in the world is three times that of humans. In the meantime it has also been shown that dogs were domesticated before the emergence of agricultural societies. Today the number of dogs worldwide is put at around 700 million to one billion. As a result of these long-term processes and in contrast to the number of domesticated animals, the number of wild vertebrates in the study is described as "vanishingly small".

As a third point, the research team describes how the settlement of islands by humans has affected. Accordingly, the associated relocation of species was so extensive that archaeologists speak of "transported landscapes". With the humans, fire and clearing as well as new species came to the islands and with them the threat to the original animal species from imported predators.

Even the Romans brought plants with them

As a final point, the study describes the effects of increasing trade with the beginning of the Bronze Age. Associated with this was a period of intensive agriculture in response to population growth and emerging markets throughout the Old World. In the Middle East, deciduous trees were replaced by evergreen holm oaks, and the native forest was turned into cultivated land with the introduction of crops such as olives, grapes and figs. Around 80 to 85 percent of the arable land in the Middle East was used for agriculture 3,000 years ago, according to a study cited in the present study. The research team also points out that plant species in ancient French forests that are believed to be native are very similar to species that once grew in Roman sites. The study also points to a recent estimate that at least 50 new food crops - mostly fruits, herbs and vegetables - were introduced to Britain during Roman times.

Lead author Nicole Boivin believes that the archaeological evidence is important for recognizing and understanding the profound impact man has had on his environment. “If we want to know more precisely how we can best protect our nature and conserve species, we have to change our perspective. Perhaps we should think more about how we can ensure clean air and fresh water for future generations than about how we can restore the earth to its pristine state. Humans have simply shaped the ecosystem for too long for that. ”Nicole Boivin also emphasizes the importance of the findings for the current climate protection debate. “Cumulative archaeological data show: We were and are something like the constructors of the ecosystem. The question is what kind of ecosystem we are creating for the future. Will it support the welfare of our own species and that of other species, or will it result in large-scale extinction and irreversible climate change? "

PM / CET