Hong Kong Cattle: Remnants of a Unique Genetic Lineage?

I have been posting photographs taken in the 1960s on the Facebook Group, Hong Kong in the 1960s. Recently I added several taken on a walk from what was then the town of Tai Po east along the northern shore of Tolo Harbour in the New Territories. The next one in the series is of an ox tethered in the corner of a field but before posting it I realised that I knew nothing of the cattle, other than the dairy cows, of Hong Kong. A Google search found a paper published this year which throws some light on their origin.

A photograph I took in early 1966 near Tai Po in the
New Territories of Hong Kong

In the years up to the 1980s, when Hong Kong had an active agricultural economy, local farmers used cattle and water buffalo as draught animals; a single ox* pulling a plough or parked on the edge of a holding to graze was a common sight throughout the rural areas. They were not kept nor bred for milk or meat. As agriculture virtually died out in the face of a massive building programme, some of the remaining draught animals became feral often to the still-continuing inconvenience and annoyance of the human population as they wander through the country side and country parks, into towns and onto roads. Estimates of the current cattle population exceed 1,200. Official reports described them in the 1960s as ‘local brown cattle’ with local used in the sense of local to south-east China. Other reports describe them as ‘Chinese brown cattle’.

Ploughing paddy fields in Hong Kong in the 1960s
From Rob Taylor's family collection and posted in the Facebook Group:
Hong Kong in the 1960s

Completely separate and isolated populations of cattle also existed until relatively recently. They provided milk for the European population. Not surprisingly, these dairy farms held dairy breeds originally from Europe. In the 1960s, the dairy farms in Hong Kong had mainly Friesians. The study raises interesting points on the history of dairying in Hong Kong but that topic will have to wait for a future article, suffice it to say that what started as a plan by the father of tropical medicine grew into something very big indeed.

Given the presence of dairy cows in Hong Kong for many decades it is not surprising that when the genomes of cattle sampled from the feral Hong Kong population were compared with those of other breeds, evidence of genes from European breeds was found. At some time in the past cattle from the dairy farms must have bred with ‘local’ animals albeit in small numbers.

Another unsurprising finding was that the feral Hong Kong cattle, not having been selectively bred for milk or beef, were genetically diverse. However, the main finding from the research described in the paper was that the population is genetically distinct ‘from other taurine, indicine and crossbred cattle populations’, and showed evidence of a significant contribution of wild bovine species to their genomes.

Given the morphological characteristics of a shoulder hump and a large dewlap, the lack of a match to taurine breeds (essentially breeds derived from the aurochs and referred to as Bos taurus or Bos taurus taurus, of western and northern Eurasia) would be expected. However, the lack of genetic similarity to any breeds of indicine cattle (domesticated from Bos taurus indicus or Bos indicus in southern Asia) does seem more unexpected. The authors of the paper concluded:

We showed that Hong Kong feral cattle, are distinct from Bos taurus and Bos indicus breeds. Our results highlight the distinctiveness of Hong Kong feral cattle and stress the conservation value of this indigenous breed that is likely to harbour adaptive genetic variation, which is a fundamental livestock resource in the face of climate change and diversifying market demands.

There is, as the authors also suggest, the possibility that the Hong Kong cattle represent a separate domestication to that or those which occurred in India, for example, from a wild indicine ancestor at some time in the past.

I have some qualms about this paper. I am unqualified to comment on the molecular genetics but I do wonder if the Hong Kong cattle (minus the small contribution of genes from European dairy animals) are simply representative of a type of beast found throughout south-eastern China as a draught animal. Agricultural practice does not stop at political borders and there was free flow of supplies and livestock between Hong Kong and the ‘mainland’^†. It seems inconceivable to me that the Hong Kong feral cattle are something special to Hong Kong. Surely they are the remnants of a much more widely distributed domestic animal? Are there any draught animals still used in southern China, or any feral populations that could be studied?

This paper then opens the door to further research using additional techniques. The authors end with:

While showing that the H[ongK[ongF[eral] are genetically different from other cattle populations, additional unbiased data, including mtDNA, Y chromosome and whole genome sequences are necessary to better define the origins of the HKF cattle and explore whether they may be traced to an independent domestication event.

Do Hongkongers now have to recognise their pesky feral cattle as a rare breed worthy of preservation both as a cultural memento and as possessing a unique set of genes?

New Territories, Hong Kong, late 1967/early 1968

*I am using ox here in the wide sense, not that of a castrated male used for draught purposes. Other than ox and its plural oxen there is no singular noun in English to describe male and female, young and old cattle.

†In supplementary material published alongside the main paper, the authors appear to be confused not only on the history of agriculture in Hong Kong in the latter half of the 20th century (it went on later than the 1950s, and still does in a very small way) but also on trade. They suggest that the flow of livestock into Hong Kong from mainland China ceased when the UN imposed an embargo in 1951 during the Korean War. That is incorrect. Britain and therefore Hong Kong only imposed a ban on the export to China of militarily strategic goods. Only the U.S.A. imposed an embargo on the import of Chinese goods—one that was maintained until 1972. Goods made in Hong Kong in during that period had a certificate of origin that had to be presented to U.S. customs in order for souvenirs to be imported by returning tourists. Brits in Hong Kong viewed with great amusement the absence of American tourists from stores selling mainland Chinese goods and the efforts of some to get the purchases they did make into the U.S.A.

Barbato M, Reichel MP, Passamonti M, Low WY, Colli L, Tearle R, Williams JL, Marsan PA. 2020 A genetically unique Chinese cattle population shows evidence of common ancestry with wild species when analysed with a reduced ascertainment bias SNP panel. PLoS ONE 15(4): e0231162. https:// doi.org/10.1371/journal.pone.0231162

Extinction of Pollinating Insects and the History of Agricultural Improvement

There were numerous papers of interest in 12 December issue of Science. Amongst them was one on the history of the disappearance of pollinating insects from the British countryside by Jeff Ollerton, Hilary Erenler, Mike Edwards and Robin Crockett of the University of Northampton*. They used 494,117 records held by the Bees, Wasps and Ants Recording Society (BWARS) and defined locally extinct species as those not recorded for at least 20 years, despite extensive efforts by naturalists. Twenty-three bee and flower-visiting wasp species have become extinct in Britain since the mid-19th century including ones that were widespread. 

The analysis shows clearly that the most rapid phase of local extinction began in the 1920s, suggesting that changes agricultural practices that were or had been taking place were responsible. The authors suggest the import of guano in the latter half of the 19th century hit bee and wasp populations in two ways, firstly by increasing grass growth at the expense of wild flowers and, secondly, by obviating the need for strict rotational cropping. Rotational cropping à la ‘Turnip’ Townshend involved a fallow year—good for nectar-rich ‘weeds’—and a legume year—good for long-tongued bees.

From Science 12 December 2014

The proportion of permanent grassland also increased dramatically during the late 19th and early 20th century. Even before the massive effort of the 2nd World War to make Britain self-sufficient in food, lessons from the 1st World War were being applied in the 1920s and 30s to increase productivity on British farms. The authors point out that the Haber process (always called the Haber-Bosch process in my day and a favourite question in chemistry exams) allowed the industrial manufacture of nitrogen fertilisers and led to the further decline of wild flowers.

One statement, I was somewhat surprised about is: …beginning in the 1920s, before the agricultural intensification prompted by the Second World War, often cited as the most important driver of biodiversity loss in Britain. I think those who were aware of the history of agricultural development in Britain would have known that the changes were already well under way in the 1920s and 1930s, not just the 1940s. 

The chapter ‘Grassland Research’** by Frank Raymond (1922-2012) describes the changes that occurred in grassland from the 1800s to the 1970s. The records used by Ollerton and his colleagues begin during the agricultural depression of the last quarter of the 19th century when the productivity of British grasslands deteriorated until the 1914-18 War. So pollinating insects would never have had it so good. A great deal of land was ploughed up for arable farming during the War. After the war, the drive to adapt the system of ley farming (a period of grass-growing in a rotation of crops) to the establishment of more persistent and productive grasses really took off. This drive was led by Sir George Stapledon FRS and his Welsh Plant Breeding Station. Because of the close links maintained with leading farmers the new practices and varieties of grass spread quickly since productivity was so markedly increased. However, this is where there appears to be a dichotomy between grassland productivity and the results of the study on pollinating insects. There was another Depression in the 1930s and the improvements that were available could not be adopted. Stapledon’s survey of 1937/38 showed only a small percentage of grassland was fully productive, huge areas had reverted to scrub and much of the land went untenanted. It could be argued that this should also have been a boom time for pollinating insects. However, according to the results obtained, extinction continued apace. One explanation is that there is a delay between the introduction of new practice and extinction. Indeed, the paper includes this cautionary note:

Our study adds to a debate on the rates and causes of regional and country-wide extinctions of British biodiversity (including invertebrates, vertebrates, and plants) and the limitations imposed by data quality. The available data for bee and flower-visiting wasp extinctions within Britain show that there are deep historical roots to this loss in pollinator diversity that correlate with transformations of land management related to changes in agricultural policy and practice, a conclusion also drawn by these other studies. Agriculture accounts for 70% of British land use, strongly suggesting that this relationship is causal, though the exact drivers of extinctions are clearly multifactorial and complex. For example, for some species there may have been a mismatch in the timing of extinctions in relation to specific agricultural changes (an “extinction debt”) that we cannot currently identify.

Notwithstanding the outstanding questions on timing, and ignoring the major changes in arable farming and the loss of hedgerows, there is no doubt that the system we ended up with in Britain—intensive grassland production, geared to the output of milk and meat and based on rye grass monocultures, must have had an effect on the abundance of pollinating insects and on the survival of species that depend on plants that were eliminated by such systems. I had that same sinking feeling in the pit of the stomach when I looked at our fields at the Hannah as I do when looking at agricultural monocultures throughout the world—oil palm, rubber, tea, coffee, wheat, maize etc. etc. My question to my former and late colleagues, Malcolm Castle and David Reid, was always whether we could incorporate more traditional grassland plants. The answer in the 1980s was ‘No’ as they explained why. Would the answer in 2014 still be ‘No’ and if so, are the present conservation measures on farms sufficient not only to prevent further loss of biodiversity but also to enable the recolonisation by pollinating species that have become locally extinct over the past 100 years or so?

-------------------

*Extinctions of aculeate pollinators in Britain and the role of large-scale agricultural changes. 
Ollerton et al. Science 346, 1360 (2014); DOI: 10.1126/science.1257259 

**Raymond, WF. 1981. Grassland Research. In Agricultural Research 1931-1981, ed Cooke GW. pp 311-323. London: Agricultural Research Council.