From megafauna extinction to the London Underground mosquito: how human activity drives evolution

A tragically extinct bit of megafauna. Image: Hulton Archive/Getty.

When scientists examine the impact of humans on the planet, the focus is mainly on the extinction of species. But increasingly researchers are looking at the idea that humans, through animal domestication, relocation and hunting, have become an evolutionary driving force that has led to new species, new traits and novel ecosystems.

A new paper, recently published in the Proceedings of the Royal Society B, argues that if we are to preserve the biodiversity of life that we value, we need to understand both the nature of this human-driven creation – a process known as speciation – as well as the effects of human-driven extinctions.


A drive to extinction

Look at humans’ effects on Earth’s plant life. Over recent decades, the amount of new plant growth each year across the world appears to have been relatively constant. However, between 25 per cent and 38 per cent of this fresh plant growth is appropriated by humans – for food and other purposes – reducing the amount available for millions of other species.

Thomas Crowther and colleagues at Yale University estimated that before the industrial revolution there were 6bn trees on Earth. There are now only 3bn. This deforestation and the conversion of land to produce food, fuel, fibre and fodder, combined with targeted hunting and harvesting, has resulted in a rate of species extinction some 100 to 1,000 times higher than would have been expected without human intervention. This probably constitutes the beginning of the sixth mass extinction in Earth’s history – an enormous impact on the planet and one reason why many scientists have declared that we have entered the Anthopocene Epoch.

Species removal isn’t a random process: a disproportionate number of those driven to extinction are the larger animals, both on land and at sea. This “megafauna extinction” began 50,000 years ago: unbelievably, half of all large-bodied mammals worldwide, equivalent to 4 per cent of all mammal species, have been lost in that time. And extinctions are not just confined to mammals: since 1500CE there have been 784 documented extinctions, including 79 mammals, 129 birds, 21 reptiles, 34 amphibians, 81 fish, 359 invertebrates and 86 plants.

Domestication and relocation

Humans have also domesticated around 474 animals and 269 plants to meet their needs, and this has led to the emergence of new species. Of the world’s 40 most common agricultural crops, eight can be considered entirely new species, just as animal domestication has created new species of animals such as the dog and domestic pig.

Animal domestication has also led to a major shift in animal distribution. According to Vaclav Smil of the University of Manitoba, of the weight of all the planet’s land mammals, humans make up 30 per cent, domesticated animals make up 67 per cent, and wild mammals just 3 per cent. Organisms have also been transported around the world – including crops, domesticated animals, and pathogens such as viruses and bacteria. This movement has led to a small number of extraordinarily common species such as the brown rat, new hybrid species such as mules, and a general homogenisation of the animal and plant life found on Earth.

There’s more to animal domestication than you’d think. Image: XKCD/creative commons.

This biological relocation started in the 16th century when species from the Old World of Europe and Asia were exchanged with those in the New World (the Americas). This is known as the Colombian Exchange, which led to the globalisation of human food, with New World crops such as maize/corn, potatoes and manioc/cassava swapping places with Old World crops such as sugarcane and wheat. Domesticated animals swapped continents, too.

Many of these plants and animals have since undergone rapid evolution in their new environments, leading to the emergence of new species. Accidental transfers from Europe occurred, too: smallpox, measles and typhus killed over 50m people in South and Central America during the colonisation of the New World. These exchanges continue today, and invasive species have become a major concern on all continents. Mark van Kleunen and colleagues at the University of Konstanz suggest that 4 per cent of plant species have been relocated around the globe, equivalent to all the native plant species in Europe.

These changes are the first of their kind since the supercontinent Pangaea separated about 200m years ago, but in fact the extent of the current epoch’s trans-oceanic exchanges are unprecedented.

Something borrowed, something new

Most ecosystems have been altered by humans, to the extent that the concept of a “natural” biome, completely free from human influence, is obsolete. This has led Erle Ellis at the University of Maryland to suggest that we consider them Anthromes – those ecosystems where most of characteristics have been reshaped by human activity. While many have undergone significant loss of biodiversity, through change they also create environments that allow opportunities for the emergence of new species.

Culex pipiens f. molestus, the mosquito species unique to the London Underground. Image: Walkabout12/creative commons.

An interesting example is that of the common house mosquito (Culex pipiens) which has become adapted to London’s underground railway and established a subterranean population of mosquitoes distinct from any other on Earth. Now called the London Underground mosquito, it has diverged sufficiently from its cousins above ground that it can no longer interbreed with them and exhibits significantly different behaviour.

So through breeding, harvesting and transport of crops and animals, and the impact of higher air and surface temperatures that result from greenhouse gas emissions, humans have, and continue to, alter the evolutionary process of the other species sharing this planet with us.

If we consider also the scientific development of diverse new biological products such as antibiotics, pesticides and novel genetically engineered organisms, humans have indeed become the world’s greatest evolutionary force capable of shaping our world by creating new species and destroying others.

If we are to help preserve the millions of species on Earth, we must consider the impact of humans in terms of these creative and destructive forces.The Conversation

Mark Maslin is professor of Climatology at UCL.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

Is Manchester doing enough to fight its air pollution crisis?

Clouds over Manchester. Image: Getty.

In June 2018, think tank IPPR released a report calling Greater Manchester’s pollution levels “lethal and illegal”. The report called on mayor Andy Burnham to urgently ramp up measures to improve air quality and for central government to give him the tools to do so.

Yet one year on, the Northern Quarter Forum has had to fight tooth and nail to close Stevenson Square to traffic for just five hours to celebrate Clean Air Week. This, coupled with the Great Ancoats Street fiasco – a multi-million pound plan to create a “European style boulevard” without any cycle infrastructure – raises red flags.

So what’s actually being done to fight Manchester’s air pollution crisis – and is it enough?

An ambitious pledge

Andy Burnham has pledged to make Manchester a leading green city in Europe. It’s an ambitious goal, considering central Manchester currently has the highest rate of emergency admissions for asthma in England – over double the national average – and Manchester is the second-worst council area in England for inhalable particulate matter. Greater Manchester is also the most congested region outside of London, with 152 roads in breach of legal NO2 levels.

The 152 roads in breach of air pollution levels. Image: TfGM.

 

All in all, 1,200 lives are lost each year due to air pollution. If that number is to be brought down to zero, Manchester better look for inspiration.

Oslo, European Green Capital 2019, prioritises pedestrians and cyclists in the city centre, and is transitioning to a completely car-free city centre. All public transport will run on renewable energy from 2020, and over 700 on-street parking spaces were removed, replaced with cycle lanes, pocket parks, and seating areas. Since the 1980’s Oslo has had tolled ring roads, and in 2017 introduced a further congestion charge.

The message is clear: becoming a leading green city means reducing the number of vehicles on the road. Switching to electric cars won’t be enough to save us, because worn tyres and brakes produce particulate matter, the micro plastic particles penetrating the deepest parts of our lungs and bloodstream.

What’s required, instead, is improved public transport – currently often both less convenient and more expensive than driving – as well as prioritising walking and cycling.

So with Burnham’s ambitious – and worthy – pledge in mind, let’s see what Manchester is doing.

Is enough being invested in public transport?

Last year, Burnham revealed his “Congestion Deal”, which includes a £122m Bus Priority Package (shepherding 9,000 more passengers a week) and spending £83m on 27 new trams. The deal also commits 40,000 more seats on commuter trains, and trebles the number of electric vehicle charging points in the region to 1,000.

Manchester’s Clean Air Plan also includes £116m government funded schemes for HGV’s, buses, taxis, and businesses upgrading to cleaner vehicles, as well as loans with preferential rates for those taking advantage of the funds.

While that may look like a lot of investment, it pales in comparison to the nearly £6bn being considered on road schemes. Moreover, research has repeatedly shown the benefits of road expansion are short-lived, “inducing” more car journeys leading to increased congestion and pollution overall.

The biggest cue for public transport in Manchester is Burnham’s recent proposal to franchise buses, bringing them back under public control. This will allow GMCA to develop a truly integrated public transport system and ensure all communities are served, not just those that are most profitable. It will also allow them to set the fares, bringing them in line with those in London; whereas it costs £4 in Greater Manchester for a single bus fare, the rate is currently capped at £1.50 in the capital.

That being said, there’s still a pressing need for more funding. When I asked the Clean Air Plan folk at Transport for Greater Manchester (TfGM) what’s the one thing government could do to help, they told me this: “To agree a devolved multi-year transport funding settlement with Greater Manchester” that includes ongoing funding, “to help us to transform public transport services to meet modern expectations as people experience in other cities across Europe.”

Despite the progress being made, as long as central government doesn’t provide new funds – and the bulk of existing funding is pumped into motorways instead – Manchester won’t become a leading green city.


Is walking and cycling being prioritised?

Burnham’s Congestion Deal also outlined a “Streets for All” approach, in which streets would be designed “for all road users” to enable alternatives to driving.

Chris Boardman became Greater Manchester’s first Walking and Cycling Commissioner in 2017 with an initial £160m earmarked to begin creating “Bee Network” safe cycle routes throughout the city – making Manchester a truly European city. That funding has now been allocated, and the first projects are coming to fruition.

However, it only accounts for 11 per cent of the £1.5bn needed to complete the Bee Network, and Boardman along with five other leading cycling commissioners are demanding government commit long-term funding to safe cycle infrastructure.

Boardman calls painted bike lanes a “waste of public money”, which encourage drivers to speed up, endangering cyclists. “Actual” bike infrastructure is needed, such as segregated cycle lanes.

He’s pointed out that government has recently agreed to spend £1.4bn on upgrading a roundabout near Bedford and building a new 10-mile dual carriageway – two projects that together may save drivers 10 minutes of travel. For the same price, Manchester could have a fully integrated cycle network that would revolutionise the way people travel around the city. Central and local government simply aren’t prioritising the measures needed to reduce air pollution.

That’s why Manchester City Council’s announcement of the £9.1m “Great Ancoats Street improvement scheme” – maintaining five lanes of motor traffic with no cycle infrastructure along one of the city’s most polluted and dangerous thoroughfares – has provoked anger and despair.

Cyclists protest on Great Ancoats Street. Image: David Saddington/author provided.

The council’s justification – “This scheme does not incorporate a segregated cycleway, as we need to balance the needs of different road users” – Illustrates a business-as-usual mindset of car dominated planning. It’s completely at odds with the scale of the challenge Manchester faces in turning around its air quality crisis.

There’s also a long way to go towards prioritising walking and cycling in the city centre. When Manchester City Council refused permission to close Stevenson Square to traffic for just five hours for the community to celebrate Clean Air Week, Northern Quarter Forum members took matters into their own hands.

They developed a plan to reroute the 13 buses that traverse Lever Street and presented it to the Highways department (essentially having done their job for them). Then it was actually Labour party councillor Angeliki Stogia who took the reins and pushed the request through.

Apart from Stogia, this lack of support for a resident’s group advancing what should be the council’s agenda is troubling. This, along with Great Ancoats Street, suggests a council not taking a “Streets for All” approach seriously, wand lacks the will to prioritise alternatives to driving in the city centre.

Is a congestion charge being introduced?

In the past year, the main focus has been developing a “Clean Air Zone”, covering all of Greater Manchester. The scheme would charge the most polluting buses, taxis, heavy and lights goods vehicles entering the zone.

This Clean Air Zone isn’t a congestion charge because it doesn’t charge polluting private vehicles. However, congestion charges are shown to be highly effective.

When Stockholm introduced its congestion charge 11 years ago, it was dubbed “the most expensive way ever devised to commit political suicide.” The charge began with just 25 per cent public approval – but when congestion dropped by 20 per cent, public opinion changed rapidly. After a seven month trial period, a referendum made the scheme permanent, and public approval now stands near 70 per cent. Revenue from the scheme has funded new metro lines and active travel improvements.

TfGM argue that charging private cars will hurt the poorest in society. However, ONS data show that while nearly all households in the richest 10 per cent by income own a car, just a third of those in the lowest 10 per cent own one. And nearly all homeowners have at least one car, compared to less than half of households in social housing.

In reality, households on lower incomes are far more likely to rely on public transport, and are disproportionately impacted by poor air quality.

The elephant in the room: the airport

Burnham has pledged to make Greater Manchester carbon neutral by 2038.

It’s difficult to imagine how this is possible, considering that Manchester Airport – 65 per cent owned by Manchester City Council – is expanding. Over the next 20 years, it plans to double passenger numbers.

Globally, aviation emissions are growing so quickly that by 2020 they’re projected to be 70 per cent higher than in 2005 and are currently 26 per cent higher than in 2013. If it were a country, global aviation emissions would be within the top 10 emitters. Here in Manchester, Pete Abel of Manchester Friends of the Earth says the current airport expansion plans would blow “our carbon budget twice over”.

A lack of follow-through

The stakes are high, the consequences dire. Strong, decisive action is required to rid Manchester of its poisonous air.

While Burnham has the vision, he doesn’t have the power. Without buy-in and consistent action from the 10 councils as well as central government, there’s only so much that can be accomplished – and it won’t be enough.

Public transport must become convenient and cheaper than driving. All city streets must enable walking and cycling. Mancunians – as well as city dwellers around the country – must hold elected representatives to account, let them know "business as usual" is no longer acceptable, and demand action to match the rhetoric.

An earlier version of this article was originally published by Manchester Confidential