Introduction

The human foot, though designed to bear weight and facilitate bipedal locomotion, also shows the combined effects of heredity and acquired lifestyle. Foot morphology is influenced by specialized occupation or specific usage’s Adaptation in shape, and modifications in soft tissue and osteological components of the foot to large extent are dictated by kinesiological stresses and strains it is subject to. Functional biomechanics play a visually verifiable and metrically quantifiable anatomical remodeling of foot structure.

The role of evolution induced ‘arch’ formations in the foot in aiding early hominids adopt a terrestrial existence, abandoning forever, the arboreal life of his simian ancestors, is a landmark milestone in development of homo. The longitudinal arches of the foot, both medial and lateral play a vital and efficient role in easing human locomotion. The ligaments, joints, bones, muscles and soft tissue components of the foot, contribute in its own unique manner, in making man alone among his mammalian cousins, to have mastered the art of walking on hindlimbs 1 as units. The liberation of the forelimbs from its pithecoid compulsions for assisting locomotion,has furthered hominid cerebration to discover its latent potential.

The question raised here is, are these time honoured evolutionary anatomical features of the foot absolute? Can prolonged and sustained strain induced by specific usages such as tree climbing2, influence the foot structure to revert to its simian prototype? Are these changes, if any measurable3? To answer some of these queries, we undertook a study of footprints of adult males drawn from communities that engage in tree climbing as an ancestral and hereditary calling.

The plantar footprint is a unique record of the weight bearing status is man. The print impress itself is a metrically assessable permanent database, which can be used to determine the functional efficiency of feet. Evaluation of the hemi-dome (hollowness) produced by the medial edge of the human foot, essentially the measurements of the components of the medial longitudinal arch4 should present us with data,which can

39.95 mms, 53.03 mms and 2538 sq mms for left side. (length, breadth, height and surface area). In controls the same parameters showed 70.14 mms, 27.34 mms, 49.7 mms and 1345 sq mms for left and 72.2, 27.4, 49.81 and 1391.89 sq mms for right foot.

Table 1:Mean of age of normal and tree climbers with mean of experience (years)
Normal (age)	Mean	Std. Error of Mean
	40.74	051
Tree Clibers(age)	42.92	1.11
Experience(Tree climbers)	20.14	1.15

Table 2: Mean of age parameters of Left and Right Foot of Normal and tree climbers (with Standard Error of Mean)
Normal	Left		Right
	Mean	Std.Error of Mean	Mean	Std.Error of Mean
A.Lenght	70.14±	2.08	72.20	2.71
B.Breadth	27.34	1.28	27.40	1.19
C.Height	49.70	1.19	49.81	1.26
D.Surface Area	1345.06	98.26	1391.00	99.88
Tree Climbers
A.Lenght	88.63	1.19	89.00	1.15
B.Breadth	39.95	1.00	39.02	0.74
C.Height	53.03	0.69	53.29	0.64
D.Surface Area	2538.82	84.28	2587.97	76.20

There is an obvious increase in all parameters, length, breadth, height and surface area in climbers compared to controls. It is also noted that the increase is directly proportional to the number of years of practice of the profession. However, oddly, the increase – trend gets arrested with the climbers attaining about 3 decades experience in profession, in fact, there is an overall dip in all dimensions thereafter. The decrease is seen in length, breadth and increase in arch height. Graphs and sketches and are presented as Figures I to IX.

Callosities were found pressure spots on plantar surface and on the medial edge dermal changes could be not just due to the stresses transmitted by climbing, but also to the friction and tribadic pressures brought about by rapid descent from the tree tops.

Fig-I: Diagram showing increasing length (A), breadth(B) & Surface Area(D) in experienced Climbers.

Fig-II: Length-Comparison between normal and tree climbers. & Fig-III: Breadth-Comparison between normal and tree climbers.

The results of statistical analysis of data using students unpaired ‘t’ test reveals that the ‘P’ value is highly significant in the parameters of length, breadth and surface area for both feet. The P value for arch height is significant for left foot, and highly significant for the right (Table 5 & 6).

Fig-VIII: Height-Percentage increase in tree climbers compared to normal & Fig-IX: Surface Area-Percentage increase in tree climbers compared to normal.

 

Table 5: Students unpaired ‘t’ test for equality of means
		‘t’ test for Equality of Means		Inference
		t	Sig.2 tailed
Left	A.Lenght	-2.597	0.011	Significant
	B.Breadth	-3.047	0.003	Significant
	C.Height	-1.435	0.154	Not significant
	D.Surface Area	-2.055	0.043	Significant
Right	A.Lenght	-2.234	0.028	Significant
	B.Breadth	-2.740	0.007	Highly Significant
	C.Height	-0.681	0.498	Not significant
	D.Surface Area	-2.609	0.009	Highly Significant

 

It is our inference that the foot dynamics and kinesiological exertions strain the factors maintaining the medial arch, the stress being overcome through a generalized augmentation in size and strength through intrinsic physiological compensatory counteractions. The failure of compensatory changes, with age and exposure (beyond 3 decades) leads to an arrest of these mechanisms, which now show a reduction in dimensions (and probably strength too.) The continued increase in arch height is mainly due to permanency of osteological changes in the foot architecture. The probable development of pressure induced epiphysis or bony spurs or buttresses in the tarsi through usage make the morphological adaptations in these bones permanent. The medial arch in experienced tree climbers is raised, not so much by the fascial inputs, but remains so by the rigidity of the deformed bony arch base.

It is also interesting to note that, accidental falls and fatalities that are recorded from time to time from groves, usually involve very experienced and old climbers. The mystery, why an experienced and highly skilled labourer should slip, may now be explained through our observations that, there is abrupt failure of arch resilience after 30 years climbing, evidenced in the rapid dip in dimensions of the hollowness.

In recent times, with falling economic returns from once cash – rich plantation industry, coupled with other factors – the rapid dwindling of able bodied men ready to stick to ancestral occupations (with availability of newer more lucrative and less strenuous avenues of income), and the palpable positive out come of free education for all, along with constitutional guarantees to better opportunities for the tribals, backwards and deprived segments of the populations it is very possible that decades hence, the complete lack of pluckers may drive the palm industry to seek totally mechanical means of cultivation. Studies such as this one may serve as retrievable records of the morphometrics of these ‘dying’ communities.