Ice Adhesion. Группа авторов
trended towards not only a colder more glaciated world, but also increased amplitude and frequency between cool and warm periods, as determined through oxygen isotope analysis of ice core samples [22]. Many of the major developments in hominin evolution have been coincident with the intensification of Northern Hemisphere glaciation, as shown in Figure 1.1 [26].
Adaptations to the increasingly unpredictable and unstable environments of the late Neogene and Quaternary periods might in fact be part of what it means to become a human in the Darwinian sense [26, 27]. The morphological and behavioural traits of terrestriality, bipedalism, dietary flexibility, tool use, omnivory, large brains, long-distance migrations, and the birth of dependant children, thought to characterize Homo sapiens have all been linked to fluctuations in Earth’s climate [23]. The environmental selection pressures led to evolutionary bottlenecks that, evidently, only our ancestors were able to pass through. Tool use and increased brain size specifically have been linked to periods of glaciation. The earliest evidence for the use of stone tools has been found in the Ethiopian region of Gona, where artifacts have been dated to 2.6 million years ago [28]. The first known use of tools coincides with the onset of Northern Hemisphere Glaciation 2.7-2.5 million years ago [29, 30]. As resources became scarce with falling temperatures, only those early human ancestors capable of constructing and utilizing tools for increased efficiency survived. Dramatic increase in the size and complexity of the brains of human ancestors, a process known as encephalization, also began around 2.6 million years ago. The average brain size increased from 600 mL to about 1 L. It is hypothesized that the cooler climate during the Northern Hemisphere Glaciation allowed for time hypermorphosis (or prolongation of the growth period), leading to the increased brain mass [31].
Evolution of Homininae continued through the first appearance of a species in the Homo genus: Homo habilis just over 2 million years ago, Homo erectus around 2 million years ago, and Homo ergaster around 1.9 million years ago [32]. Homo erectus persisted as a species for more than a million years until diverging gradually into new species including Homo neanderthalsis in Eurasia around 400,000 years ago, and the anatomically modern human being, Homo sapiens, in Africa between 300,000 and 200,000 years ago [33, 34]. Most of the past 350,000 years in East Africa have been a period of strong climatic oscillation, meaning that Homo sapiens with the capacity to create new and diverse tools, wide social networks, and the ability to plan are evolutionarily adept to diverse survival challenges [19, 23]. Homo sapiens dispersed from Africa in multiple waves, with the first anatomically modern humans reaching Mediterranean Europe between 45,000 and 43,000 years ago [35]. Humans and Neanderthals would go on to co-inhabit Eurasia for 2,000-6,000 years until the climate drastically changed once more towards a period of glaciation [33]. Once again the conditions which allow for the appearance of surface ice on Earth shaped the evolution of the genus Homo, creating a scarcity in resources for both Homo sapiens and Homo neanderthalsis. Neanderthals seem to have died out in Europe about 39,000 years ago. Whereas Humans employed large social networks comprised of oral and non-oral communication to collect and share materials, Neanderthals lived in a much smaller world, collecting raw materials exclusively from their local area [36]. This final evolutionary bottleneck is one of the key reasons for Homo sapiens survival while our evolutionary cousins did not.
1.1.3 Modern Man Carves Ice
Homo sapiens have displayed behavioural modernity (often defined as four sets of behaviours: (i) abstract thinking; (ii) depth of planning; (iii) behavioural, economical, and technological innovativeness; and (iv) symbolic behaviour) for approximately 50,000 years [37]. In the 50 millennia of modern behaviour, humans have dispersed across much of the Earth, including areas where the climate allows for the accumulation of surface ice throughout a portion of the year [38]. Yet, there is little evidence of ancient technologies to mitigate the effects of surface ice on daily human life; it appears that ice accumulation did not hinder the activities of the average early human. In fact, mitigating the effects of surface ice accumulation and especially preventing surface ice accumulation are decidedly modern human endeavours, as shown in the timeline of Figure 1.2.
Perhaps human’s first attempt at simply overcoming the effects of surface icing occurred in Scandinavia, where the last glacier retreated 12,000 years ago. In Southern Europe, human culture had adopted iron and bronze tools to farm and build houses, villages, and cities. The Stone Age in circumpolar Europe, on the other hand, would continue until the year 400 in the current era. Whereas everywhere else in Europe at this time, from Ireland to Transylvania and the Pyrenees, was covered in deciduous forests of oak and broadleaf trees, Scandinavia had only a pre-Boreal forest of birch and spruce. Nonetheless, people survived in the harsh Scandinavian climate by fashioning skis. A ten-foot Finnish ski which was preserved in peat has been dated to 7000 BCE. Skis such as these, made of carefully selected compression pine (obtained from curved tree trunks), turned the vast frozen waterways into an efficient method of hunting and transportation. Skis have been used militarily since at least 1200 CE, when King Sverre ordered local civilians to spy on enemy positions on ski. Formal ski troops later formed, with the earliest illustration of such being dated to 1619 which shows Swedish soldiers guarding against the Russians. Ski troops would play a considerable role in the fighting between Finland and Russia in the Second World War. The race training developed for these military ski troops would cross over into the civilian world and lead to cross-country skiing as a sport and further lead to the emergence of alpine skiing [39].
Figure 1.2 A timeline of human activities which have aided in our understanding of how to mitigate the effects of surface ice accumulation. The first industrial revolution accelerated our understanding of mechanical and electrical cooling. The second industrial revolution accelerated our need for anti-surface icing strategies due to advancements in transportation. BCE denotes before the current era.
Horse-powered transportation also necessitated a solution to the problem of surface ice accumulation. In the time between the introduction of iron horseshoes around 1000 CE and the beginning of the automobile-era, numerous solutions were described in farriery literature to assist the working horse in gaining traction on ice [40]. This includes the addition of protruding metal calks to the underside of the horseshoe, much like studded tires would assist in automobile traction in the twentieth century [41].
Human’s understanding of ice accumulation began to take shape during the First Industrial Revolution. This period of rapid mechanization also ushered in new chemical manufacturing processes, in turn fuelling accelerated research into the nascent field of modern chemistry. In 1756, Abbé Nollet described a method of artificially cooling wine by dissolving sal ammoniac (ammonium chloride) in water [42]. Coined “frigorific mixtures”, the apothecary Richard Walker’s “An Account of Some Remarkable Discoveries in the Production of Artificial Cold” concluded that the cold temperatures produced upon mixing were a result of sensible heat being transformed into the latent heat necessary to form the new phase upon dissolution of the salt [43]. The concept of artificial cooling via an ice-salt solution was employed in the experimental setup of Sir Charles Blagden with which he concluded that: (1) turbidity raises the freezing point of a liquid; and (2) the freezing point of a liquid solvent can be depressed by the addition of a solute [44]. The mathematical formulation of the inverse linear relationship between the solute concentration and freezing point temperature depression of the solvent would later be called Blagden’s Law [45].
Mechanization in the First Industrial Revolution was realized using: steam engines powered by coal, water wheels placed in a flowing river, or pneumatically by air compressed using a waterfall. Wolfe and Baker described an example of the latter for the Royal Society in 1761. The giant Hiero’s fountain built at the Chemnicensian mines in Hungary used a 260-foot tall column of water to compress air. Wolfe and Baker noted that upon opening the stopcock, the air rapidly expanded producing enough cold to precipitate snow out of the air’s