Tag Archives: climate change

My maternal ancestors – from Eve via ice age Europe to Victorian England

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In an early post on this blog, I summarized my maternal-line ancestors and where and when they lived. In the last 6 years, there have been substantial revisions to estimates of the dates associated with these mitochondrial DNA (mtDNA) haplogroup founders, and revisions to the mtDNA haplogroup tree (deep-maternal-ancestry-and-mtdna) and this post provides an update. I am a member of mtDNA haplogroup U5, which is one of nine native European haplogroups stemming from haplogroup U which most likely arose in the Near East, and spread into Europe in a very early expansion. The presence of haplogroup U5 in Europe pre-dates the last ice age and the expansion of agriculture in Europe. Today, about 11% of modern Europeans are the direct maternal descendants of the founder U5 woman. They are particularly well represented in western Britain and Scandinavia. My more recent maternal ancestors were part of the population that tracked the retreat of ice sheets from Europe at the end of the last ice age and re-colonized Britain about 12,000 years ago.

The mtDNA sequence at the root of each haplogroup arose from one or more mutations in the mtDNA of just one woman, and the age of the associated haplogroup gives the time in the past when this specific woman lived. To emphasise that the maternal clan founders were real individuals, I have used the names given to them by Sykes [1] and Oppenheimer [2] and given my own names to the more recent subgroup founders. The Table below summarizes these founders, dates and locations and is followed by brief biographies. The haplogroups are identified by the labels used in Build 17 of the ISOGG mtDNA tree which can be accessed at http://phylotree.org/ [3]. Dates in the table below have been updated using most recent available dating estimates as described in my previous post deep-maternal-ancestry-and-mtdna.

The migration path out of Africa into Europe of the “grandmothers” linking mitochondrial Eve through to Ursula (U5) is shown on a map in my previous post deep-maternal-ancestry-and-mtdna. The subsequent migration from Europe to Britain is shown in the map below.

Figure 1. Migration path of my maternal ancestors from Ursula (U5) to Viviane (410 CE). A map of the earlier migration from mitochondrial Eve to U5 is included in an earlier post.

Updated biographies of my maternal haplogroup great* grandmothers follow below.

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Australia appears to be committing climate suicide

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Media across the world have been publishing articles and photos on the catastrophic bushfires in Australia. Richard Flanagan, a well-known Australian author, published an opinion piece in the New York Times two days ago, which fairly accurately summarized the impact of the fires and the complete inadequacy of the government and political response (Australia Is Committing Climate Suicide).

Mogo, a town on the NSW south coast has been devastated by bushfires. One Mogo resident watched his 92 year old father’s house burning next door. At the time of taking this photo, he wasn’t sure where his father was. Credit: James Brickwood

Here are some quotes from the article:

“Australia today is ground zero for the climate catastrophe. Its glorious Great Barrier Reef is dying, its world-heritage rain forests are burning, its giant kelp forests have largely vanished, numerous towns have run out of water or are about to, and now the vast continent is burning on a scale never before seen.       …….

“The fires have already burned about 14.5 million acres — an area almost as large as West Virginia, more than triple the area destroyed by the 2018 fires in California and six times the size of the 2019 fires in Amazonia. Canberra’s air on New Year’s Day was the most polluted in the world partly because of a plume of fire smoke as wide as Europe.

“Scientists estimate that close to half a billion native animals have been killed and fear that some species of animals and plants may have been wiped out completely. Surviving animals are abandoning their young in what is described as mass “starvation events.” At least 18 people are dead and grave fears are held about many more. …..”

A deceased horse on a property on the outskirts of Cobargo, a town on the NSW south coast that was devastated by bushfires at New Year. Credit: James Brickwood

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Mitochondrial Eve – an update

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A recently published paper in Nature (Oct 18) has analysed the mitochondrial DNA of 1,200 indigenous Africans living in the southern part of Africa and identified the ancestral homeland of all humans alive today, the place where mitochondrial Eve lived nearly 200,000 years ago. More on that below, but first some background.

In February 2014, I did a series of posts on my deep maternal ancestors, identified through a test of mutations on my mitochondrial DNA (mtDNA) which is inherited only from the mother. These mutations allowed me to track back through time to mitochondrial Eve, the single woman from whom all humans alive today descended through their female line (mother to mother to mother….).  Specific mutations on the mtDNA define maternal haplogroups, and the founder of a given haplogroups is the specific individual woman in which the defining mutation occurred. All members of a given haplogroup trace their maternal ancestry back to this founder.

DNA tests have become much less expensive, and can include much more detailed testing. In the last three months, I’ve redone a test on my mtDNA and also on my Y DNA, which is inherited only down the male line (father to father to father….). I am still digesting the results of these tests, and will post on them in the near future.  One of the first things I discovered was that the dates associated with haplogroup founders have been revised over time, and as more and more test results are available, and that the terminology used for identifying haplogroups has also evolved.  I also came across very recent research which has pinned down the location where mitochondrial Eve lived, as well as revised estimates of the time period in which she lived.

Haplogroup U5 – the oldest of seven native European haplogroups

My mtDNA haplogroup is U5, the oldest of the seven native European haplogroups. Haplogroup U most likely arose in the Near East, and spread into Europe in a very early expansion, giving rise to seven native European haplogroups, including U5. The presence of haplogroup U5 in Europe pre-dates the last ice age and the expansion of agriculture in Europe. Today, about 10% of modern Europeans are the direct maternal descendants of the founder U5 woman, who has been given the nickname Ursula*. They are particularly well represented in western Britain and Scandinavia.

Ancestral migration path of maternal ancestors for haplogroup U5

Haplogroup U in turn is descended via haplogroups R and N from haplogroup L3, which is associated with a migration of humans out of Africa around 70,000 to 50,000 years ago. The dominant theory of human origins, the “recent African origin” theory, proposes that all modern non-African populations are substantially descended from populations of H. sapiens that left Africa after during that time period. H. sapiens most likely developed in Africa between 300,000 and 200,000 years ago, and there were at least several “out-of-Africa” migrations of modern humans, possibly beginning as early as 270,000 years ago. These early dispersals may have died out or retreated, although some paleoanthropologists argue that they possibly interbred with various other local hominid species and with later humans from “recent-out-Africa” and it just so happens that all the maternal lineages trace back to “recent-out-Africa”. Of all the lineages present in Africa, only the female descendants of Lara*, founder of the L3 haplogroup, are found outside Africa. If there had been several migrations, one would expect descendants of more than one lineage to be found.  Of course, all this could be upturned if descendants of other African lineages are found outside Africa, and can be traced back to earlier migrations.

Mitochondrial Eve (haplogroup L)

Mitochondrial Eve (mt-Eve) is a member of Haplogroup L and lived just before the divergence of macro-haplogroup L into L0 and L1–6 (see diagram below). Today the haplogroup L0 and its offshoots are found mainly in southern and eastern Africa, with particularly high frequencies among the San people (bushmen) of Botswana, Namibia and other countries of southern Africa.

Haplogroup L1 is found in West and Central sub-Saharan Africa. The descendants of haplogroup L1 are also African haplogroups L2 and L3, the latter of which gave rise to all non-African haplogroups.

Phylogenetic tree for mtDNA Haplogroup L, commencing with mitochondrial Eve, the most recent common maternal ancestor (MRCA) of all humans.

A recent paper by Chan et al. in Nature (October 2019) [1] analysed the genomes of more than 1,200 indigenous Africans living in southern Africa and claim to have identified precisely where and when the L haplogroup split into L0 and L1 and when these groups migrated from their homeland.

Chan et al. identified this homeland as Makgadikgadi, a vast wetland some 120,000 square kilometers in area, or roughly twice the area of Lake Victoria, Africa’s largest lake today. Mitochondrial Eve and her descendants lived in this region for about 30,000 years (from 200,000 to 170,000 years ago) before the L0 lineage split into its first subgroup. Today, Makgadikgadi is one of the largest salt flats in the world. Climate models suggest that, 200,000 years ago, it was a fertile oasis.  The map  shows the overall location of Makgadikgadi in southern Africa, and the following map shows  a more detailed view.

Satellite view of the Makgadikgadi salt pans. This area is located about 250 km south of Victoria Falls close to the borders of Zambia, Zimbabwe and Botswana.

Chan et al [1] date the deepest rooting L0 branch to 200,000 years ago (with 95% confidence interval 165,000 – 240,000 years ago).  I have reviewed the most recent comprehensive dating of maternal haplogroups and found that the dates in Fu et al (2012)  [2] and Behar et al [2013] were in reasonably good agreement.  I have used dates from Behar et al, which give a date of  176,700 years ago (confidence interval ± 11,300 years) for mitochondrial Eve, and 136,300 (± 11,700) years ago for L1. This is substantially earlier than the date of the recent out-of-Africa dispersal of L3 around 65,000 years ago.

The Okavango delta, in north-west Botswana, looks very similar to how Makgadikgadi would have looked 170,000-200,000 years ago. Credit: Diego Delso, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=75769486

Migrations from the Makgadikgadi homeland

The Makgadikgadi wetlands were large, wet, and lush with vegetation. They would have provided an ideal home for wildlife and for early humans, including mt-Eve. So why did some migrate?  Around 130,000 years ago, there was a major climatic shift associated with the end of the penultimate glacial period. This led to higher rainfall and created “green corridors” leading to the northeast and to the southwest.  In particular, it appears that the ancestral founder of the L1 haplogroup lived around 136,000 years ago among a group that had migrated north into Zambia, and by around 70,000 years ago her descendents had made their way north to the horn of Africa, where Lara (L3 haplogroup founder live).

The “green corridors” proposed by Chan et al [1] helped lead humans out of the ancestral homeland

Chan and his group have extrapolated the likely location of mt-Eve’s homeland from the present-day distribution of the L haplgroup in Southern Africa, and it is always possible that future data may lead to revisions of this conclusion. However, multiple sets of evidence lead to the conclusion that mt-Eve was among the ancestors of the San people of southern Africa, although of course we likely will never know for sure exactly where she lived. And this was not the only ancestral human homeland. Y-DNA evidence suggests that Y-Adam lived in West Africa in a time period even further in the past (this will be subject of a future post) and of course, there may be other ancestral homelands associated with the many other ancestral lines than the purely maternal and paternal.

The San people of southern Africa have one of the most oldest maternal DNA lineages on Earth. They share the Haplogroup L with mitochondrial Eve who lived in northern Botswana nearly 200,000 years ago.

* Bryan Sykes in his 2001 book The seven daughters of Eve gave names to each of the women who founded the seven native European haplogroups, and also names to some of their ancestral haplogroups. He chose names that began with the letter by which the haplogroup was identified. Oppenheimer (The Origins of the British: A Genetic Detective Story, 2006) followed this example and also gave names to both mtDNA and Y-DNA haplogroups. To emphasise that the maternal clan founders were real individuals, who were my ancesters, I have used these names and given my own names to the more recent subgroup founders.

References

[1] Chan EKF, Hardie RA, Petersen DC, Beeson K, Bornman RMS, et al. (2015) Revised Timeline and Distribution of the Earliest Diverged Human Maternal Lineages in Southern Africa. PLOS ONE 10(3): e0121223.
https://doi.org/10.1371/journal.pone.0121223

[2] Fu Q, Mittnik A, Johnson PLF, et al. A revised timescale for human evolution based on ancient mitochondrial genomes. Curr Biol. 2013;23(7):553–559. doi:10.1016/j.cub.2013.02.044
https://www.cell.com/current-biology/fulltext/S0960-9822(13)00215-7?code=cell-site

[3] Behar D, van Oven M, Rosset S, et al. A “Copernican” Reassessment of the Human Mitochondrial DNA Tree from Its Root. Am J Hum Genet. 2012;90(5):936. doi:10.1016/j.ajhg.2012.04.007
Open ArchiveDOI:https://doi.org/10.1016/j.ajhg.2012.03.002

Australian bushfires and global warming

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At the beginning of December, 118 forest fires were burning in NSW, 48 of them out of control. The bushfire season started much earlier this year, with more than 140 fires in northern New South Wales (NSW) and Queensland, which destroyed over 600 homes and killed six people. One of these fires destroyed the Binna Burra resort in the Lamington National Park, as well as surrounding rainforest. This was followed by another outbreak of bushfires in November, with more than 129 bushfires in NSW and Queensland. At least 200 houses were destroyed and four people killed.

By the end of November, around 2 million hectares (5 million acres) of bushland had been burnt, and all this before the start of summer and the traditional bushfire season  According to the Climate Council of Australia, the catastrophic, unprecedented fire conditions currently affecting NSW and Queensland have been aggravated by climate change. Bushfire risk was exacerbated by record breaking drought, very dry fuels and soils, and record breaking heat. Since the mid-1990s, southeast Australia has experienced a 15% decline in late autumn and early winter rainfall and a 25% decline in average rainfall in April and May. Across Australia average temperature has increased leading to more record breaking hot weather. Extreme fire danger days have increased.

Extensive fires currently burning in the Blue Mountains

I was in Australia in November to visit family at Noosa. A couple of days before my trip, I was stunned to read on the web that Tewantin, the suburb next to Noosaville where I was headed, was being evacuated because of the threatening bushfire.

While I was in Noosa, the residents of Noosa North Shore were evacuated because of another fire, as were the people who lived around Lake Cooroibah, about 10 km upstream on the Noosa River. Some days later, I drove up to Cooroibah where I saw extensive burnt areas of bush.  The photos below show the fire damage. Most of the trees are evergreen eucalypts (gum trees) and the dead leaves from the heat are orange or brown. Though it may look like autumn colours to those from the Northern Hemisphere, it is actually dead leaves. Most of the larger trees will regenerate, as the ecucalypt forests of Australia have evolved to adapt to fire, with thick bark, an ability to resprout along their entire trunks, and in some cases depend on fire to open their seed pods.  Animals such as the koala bear and other threatened species do not do so well, particularly when the fires are widespread and have significant impact on populations.

Bushland near Lake Cooroiba

Around 2,500 people were evacuated from about 440 homes in this area, but only one house and some sheds were destroyed. A teenage boy on his own in the house that was destroyed managed to make it into the nearby lake as the fire came over.

Burnt forest on the shore of Lake Cooroiba

The fire came quite close to this house.

There is a small housing development here, and the fire came within 50 metres of the houses. I spoke to one resident who told me he and his dog stayed, and hid when the police came to evacuate everyone.

Years ago when I lived in Sydney, there were regularly bushfires in the nearby Blue Mountains where increasing numbers of people were living. Those who stayed with their homes were able to put out spot fires, fill gutters with water, and deal with floating embers. Those who left their houses often returned to find the houses burnt down. Of course, those who underestimated the intensity of the fire and stayed sometimes paid with their lives.

So it’s a difficult call whether to stay or leave. One time in the 1980s, I went up to the Blue Mountains to help some friends during a bushfire. We stayed with the house and fought the spot fires successfully. The house was on a ridge and the wind drove the fire up the side of the ridge and over the house. As the fire approached, the heat increased and it became very difficult to breathe due to smoke. We all wrapped ourselves in wet towels and lay flat in the gutter of the road where the air was clearer. The fire passed over us and we were OK, though somewhat terrified. Australian eucalypts have a lot of eucalyptus oil in the leaves, and the heat vaporises this into the air, so that fires will spread at tree height, and in the most intense fires will leap across the tops of the trees as the eucalyptus oil above the trees ignites.

Fire damaged bark on a tree trunk

Returning to 2019, although Australia has always had devastating bushfires in some years, scientists and fire service chiefs have stated that the fire risk this year is the highest ever. Back in August, the The Bushfire and Natural Hazard Cooperative Research Centre (BNHCR) warned that New South Wales and Queensland and some other parts of Australia faced higher than normal fire potential. The Australian Bureau of Meteorology publishes a Forest Fire Danger Index (FFDI) which combines measurement of temperature, humidity, rainfall, evaporation and wind speel. Their cumulative winter index for 2019 (BOM), published in September, shows the overwhelming majority of the country, with a few exceptions in Victoria, central Queensland and western Tasmania, is experiencing between “above average” and “highest on record” fire conditions when compared with the average since 1950 (see map below). The measured FFDI values were in the extreme category (over 75) across large areas, reaching the catastrophic category (FFDI values of 100 or above) at some locations in New South Wales.

In line with the measured rise in average annual surface temperature over recent decades, the FFDI has been increasing across most of eastern Australia. Projections by Bureau of Meteorology Scientists recently published in Nature (ref), continue to show an increase in FFDI values due to increasing greenhouse gas emissions over the course of the century. This result is robust across a range of climate projection models, methods and metrics. This means that the number of days in the year where the FFDI value represents “Very High” fire danger will increase substantially over the next 50 years.

What is the political response to all this?  The Australian Prime Minister Scott Morrison is a climate denialist and stated that there was no evidence to link the increased bushfire risk to climate change. He went further and stole a line from US poliiticians, telling the nation “Now is not the time to discuss possible causes of the fires, instead we must pray for the victims.”

Extinction Rebellion and other forms of climate protest have become more vocal recently, and Morrison recently announced hi intention to outlaw and criminalize protest by climate activists. The Queensland government is also fast-tracking laws to crack down on climate protesters.

The Australian government is also discussing how to outlaw consumer boycotts of businesses such as coal miners. They have a bit of a problem figuring out how to do that as some of the major banks and investment companies are also avoiding investment in fossil fuels.

Bushland burnt in September near Peregian Beach

Climate change and the undermining of science

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Greta Thunberg and Extinction Rebellion have been raising awareness of the urgent need to stop talking and start acting on global warming. The evidence that global warming is real and that it is human-caused is now overwhelming, but the public debate is regularly swamped by science deniers who in most cases clearly simply ignore or are ignorant of the evidence, and often are clearly clueless about how to assess evidence, or even what constitutes evidence.

The first illustration below, from a recent Economist issue, summarises the rise in average temperature across the earth’s surface in 2018 compared to the average for 1951-1980.

Many deniers claim that the current rising temperature is natural, resulting from ice age cycles or orbital variations of the earth. The graph below shows how current CO2 levels are dramatically higher and rising faster than in any interglacial period over the last half million years. And our best climate models predict temperature rises associated with CO2 levels which match measured temperatures over the last 40 years. If the impact of CO2 is excluded from the models, it is not possible to explain the observed rise in temperature (see graph below).

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Latest data show accelerating rise in carbon dioxide

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A week ago I posted on climate change and Australian politics (Climate change) and included a graph of the Keeling curve showing the increase in atmospheric carbon dioxide concentration. I was a week too early, as the Mauna Loa Observatory in Hawaii has just released its latest results showing that atmospheric carbon dioxide concentration hit 415 ppm on June 3rd (two days ago). This is the second highest annual rise in the past six decades.

May is the most significant month for global carbon dioxide concentrations because it is the peak value for the year, before the growth of vegetation in the northern hemisphere starts to absorb the gas from the air. The seasonal peak and fall can be seen in the Keeling curve, named after Charles Keeling, who started the observations on Mauna Loa in 1958 because of its isolation in the Pacific Ocean.

As recently as the 1990s, the average annual growth rate was about 1.5ppm, but in the past decade that has accelerated to 2.2ppm, and is now even higher. This brings the threshold of 450ppm closer sooner than had been anticipated. Concentrations of the gas have increased every year, reflecting our burning of fossil fuels.

Scientists have warned for more than a decade that concentrations of more than 450ppm risk triggering extreme weather events and temperature rises as high as 2C, beyond which the effects of global heating are likely to become catastrophic and essentially irreversible on a human time scale.

The Scripps Institute of Oceanography has a video animation showing the dramatic rise in carbon dioxide concentration from the mid-20th century. The screenshot below from the video shows that the carbon dioxide concentration was below 300 ppm for most of the last three centuries but started to rise dramatically after World War II.

The video then zooms out to show the Keeling curve for the last 800,000 years putting the accelerating rise in atmospheric carbon dioxide this century in stark perspective. For the evidence linking carbon dioxide rise to global warming refer to my previous post.

 

Climate change and Australian politics

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Australia recently held a Federal election in which all the opinion polls for months had shown that the Labor Party was going to win by 52% to 48% and the Liberal National Party (LNP – the coalition of conservative parties in Australia) would lose government. Over the last 6 years, the LNP government has abandoned the country’s policy for cutting greenhouse-gas emissions, and effectively dropped its commitment to the 2015 Paris climate agreement (although it is pretending it will still meet the emissions-reduction target by use of misleading statistics).  The urgency of addressing climate change became a major issue, particularly for younger people, in the recent election campaign, and The Labor party ran with a much stronger set of policies to address climate change in the recent election campaign, and this issue was a principal issue for many urban and younger voters.

The Labor party also ran with a very detailed list of policies including getting rid of some tax breaks which predominantly favoured relatively rich investors, and some tax policies on ownership of second houses which had the impact of raising house prices to the disadvantage of first house buyers. The LPNP ran scare campaigns about Labor taxes (that were largely false) and together with the concern of working class voters particularly in rural areas where coal and other mining were important, this resulted in the loss for Labor.

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