Is there a biological reason for spreading food intake into breakfast-lunch-dinner?
The three meals a day seems to be a cultural trait. Then what is the optimal number of meals a day? It is not known. Here are the results of some studies:

Reduced meal frequency:

It was found that the body can adapt to a single meal a day by modifying circulating hormone levels and glucose tolerance [1]. However it does not modify lipogenesis rates [2]. It may support cardiovascular disease risk factors [8].

Increased meal frequency:

Although there are studies that claim 5-6 meals a day help in maintenance of weight loss [3], others claim this habit increases hunger and the desire to eat and has no significant effect on fat oxidation [4]. A higher number of daily meals is recommended to the elderly suffering from cardiovascular diseases [5] because less but square meals lead to a redistribution of blood to the gastro-intestinal tract to increase absorption, which causes reduction of blood pressure [6]. 

Conclusion:

Energy balance is more important than meal frequency. As this study says [7]:


  ... there is no evidence that weight loss on hypoenergetic regimens is altered by meal frequency. We conclude that any effects of meal pattern on the regulation of body weight are likely to be mediated through effects on the food intake side of the energy balance equation.




References:


Carlson O, Martin B, Stote KS, Golden E, Maudsley S, Najjar SS, Ferrucci L, Ingram DK, Longo DL, Rumpler WV, Baer DJ, Egan J, Mattson MP. Impact of reduced meal frequency without caloric restriction on glucose regulation in healthy, normal-weight middle-aged men and women. Metab. Clin. Exp. 2007 Dec;56(12):1729-34. doi: 10.1016/j.metabol.2007.07.018. PubMed PMID: 17998028. 
Jones PJ, Namchuk GL, Pederson RA. Meal frequency influences circulating hormone levels but not lipogenesis rates in humans. Metab. Clin. Exp. 1995 Feb;44(2):218-23. PubMed PMID: 7869919. 
Bachman JL, Phelan S, Wing RR, Raynor HA. Eating frequency is higher in weight loss maintainers and normal-weight individuals than in overweight individuals. J Am Diet Assoc. 2011 Nov;111(11):1730-4. doi: 10.1016/j.jada.2011.08.006. PubMed PMID: 22027056. 
Ohkawara K, Cornier MA, Kohrt WM, Melanson EL. Effects of increased meal frequency on fat oxidation and perceived hunger. Obesity (Silver Spring). 2013 Feb;21(2):336-43. doi: 10.1002/oby.20032. PubMed PMID: 23404961. 
Ortega RM, Redondo MR, Zamora MJ, López-Sobaler AM, Quintas ME, Andrés P, Gaspar MJ, Requejo AM. [Relationship between the number of daily meals and the energy and nutrient intake in the elderly. Effect on various cardiovascular risk factors]. Nutr Hosp. 1998;13(4):186-92. PubMed PMID: 9780751. 
Westenend M, Lenders JW, Thien T. The course of blood pressure after a meal: a difference between young and elderly subjects. J Hypertens Suppl. 1985 Dec;3(3):S417-9. PubMed PMID: 2856754. 
Bellisle F, McDevitt R, Prentice AM. Meal frequency and energy balance. Br. J. Nutr. 1997 Apr;77 Suppl 1:S57-70. PubMed PMID: 9155494. 
Stote KS, Baer DJ, Spears K, Paul DR, Harris GK, Rumpler WV, Strycula P, Najjar SS, Ferrucci L, Ingram DK, Longo DL, Mattson MP. A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults. Am. J. Clin. Nutr. 2007 Apr;85(4):981-8. PubMed PMID: 17413096.